10:05 a.m.
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On 10/02/2017 11:00 AM, Yaniv Kaul wrote:
On Mon, Oct 2, 2017 at 5:57 PM, Jason Keltz <jas(a)cse.yorku.ca
<mailto:jas@cse.yorku.ca>> wrote:
On 10/02/2017 10:51 AM, Yaniv Kaul wrote:
>
>
> On Mon, Oct 2, 2017 at 5:14 PM, Jason Keltz <jas(a)cse.yorku.ca
> <mailto:jas@cse.yorku.ca>> wrote:
>
>
> On 10/02/2017 01:22 AM, Yaniv Kaul wrote:
>>
>>
>> On Mon, Oct 2, 2017 at 5:11 AM, Jason Keltz
>> <jas(a)cse.yorku.ca <mailto:jas@cse.yorku.ca>> wrote:
>>
>> Hi.
>>
>> For my data domain, I have one NFS server with a large
>> RAID filesystem (9 TB).
>> I'm only using 2 TB of that at the moment. Today, my NFS
>> server hung with
>> the following error:
>>
>> xfs: possible memory allocation deadlock in kmem_alloc
>>
>>
>> Can you share more of the log so we'll see what happened
>> before and after?
>> Y.
>>
>>
>> Here is engine-log from yesterday.. the problem started
>> around 14:29 PM.
>> http://www.eecs.yorku.ca/~jas/ovirt-debug/10012017/engine-log.txt
>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/engine-log.txt>
>>
>> Here is the vdsm log on one of the virtualization hosts,
>> virt01:
>> http://www.eecs.yorku.ca/~jas/ovirt-debug/10012017/vdsm.log.2
>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/vdsm.log.2>
>>
>> Doing further investigation, I found that the XFS error
>> messages didn't start yesterday. You'll see they
>> started at the very end of the day on September 23. See:
>>
>> http://www.eecs.yorku.ca/~jas/ovirt-debug/messages-20170924
>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20170924>
>>
>>
>>
>> Our storage guys do NOT think it's an XFS fragmentation
>> issue, but we'll be looking at it.
> Hmmm... almost sorry to hear that because that would be easy
> to "fix"...
>
>>
>> They continued on the 24th, then on the 26th... I think
>> there were a few "hangs" on those times that people were
>> complaining about, but we didn't catch the problem.
>> However, the errors hit big time yesterday at 14:27
>> PM... see here:
>>
>> http://www.eecs.yorku.ca/~jas/ovirt-debug/messages-20171001
>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20171001>
>>
>> If you want any other logs, I'm happy to provide them. I
>> just don't know exactly what to provide.
>>
>> Do you know if I can run the XFS defrag command live?
>> Rather than on a disk by disk, I'd rather just do it on
>> the whole filesystem. There really aren't that many
>> files since it's just ovirt disk images. However, I
>> don't understand the implications to running VMs. I
>> wouldn't want to do anything to create more downtime.
>>
>>
>> Should be enough to copy the disks to make them less fragmented.
> Yes, but this requires downtime.. but there's plenty of
> additional storage, so this would fix things well.
>
Live storage migration could be used.
Y.
>
> I had upgraded the engine server + 4 virtualization hosts
> from 4.1.1 to current on September 20 along with upgrading
> them from CentOS 7.3 to CentOS 7.4. virtfs, the NFS file
> server, was running CentOS 7.3 and kernel
> vmlinuz-3.10.0-514.16.1.el7.x86_64. Only yesterday, did I
> upgrade it to CentOS 7.4 and hence kernel
> vmlinuz-3.10.0-693.2.2.el7.x86_64.
>
> I believe the problem is fully XFS related, and not ovirt at
> all. Although, I must admit, ovirt didn't help either. When
> I rebooted the file server, the iso and export domains were
> immediately active, but the data domain took quite a long
> time. I kept trying to activate it, and it couldn't do it.
> I couldn't make a host an SPM. I found that the data domain
> directory on the virtualization host was a "stale NFS file
> handle". I rebooted one of the virtualization hosts (virt1),
> and tried to make it the SPM. Again, it wouldn't work.
> Finally, I ended up turning everything into maintenance mode,
> then activating just it, and I was able to make it the SPM.
> I was then able to bring everything up. I would have
> expected ovirt to handle the problem a little more
> gracefully, and give me more information because I was
> sweating thinking I had to restore all the VMs!
>
>
> Stale NFS is on our todo list to handle. Quite challenging.
Thanks..
>
> I didn't think when I chose XFS as the filesystem for my
> virtualization NFS server that I would have to defragment the
> filesystem manually. This is like the old days of running
> Norton SpeedDisk to defrag my 386...
>
>
> We are still not convinced it's an issue - but we'll look into it
> (and perhaps ask for more stats and data).
Thanks!
> Y.
>
>
> Thanks for any help you can provide...
>
> Jason.
>
>
>>
>> All 4 virtualization hosts of course had problems since
>> there was no
>> longer any storage.
>>
>> In the end, it seems like the problem is related to XFS
>> fragmentation...
>>
>> I read this great blog here:
>>
>>
https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-dea...
>>
<https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-dea...
>>
>> In short, I tried this:
>>
>> # xfs_db -r -c "frag -f" /dev/sdb1
>> actual 4314253, ideal 43107, fragmentation factor 99.00%
>>
>> Apparently the fragmentation factor doesn't mean much,
>> but the fact that
>> "actual" number of extents is considerably higher than
>> "ideal" extents seems that it
>> may be the problem.
>>
>> I saw that many of my virtual disks that are written to
>> a lot have, of course,
>> a lot of extents...
>>
>> For example, on our main web server disk image, there
>> were 247,597
>> extents alone! I took the web server down, and ran the
>> XFS defrag
>> command on the disk...
>>
>> # xfs_fsr -v 9a634692-1302-471f-a92e-c978b2b67fd0
>> 9a634692-1302-471f-a92e-c978b2b67fd0
>> extents before:247597 after:429 DONE
>> 9a634692-1302-471f-a92e-c978b2b67fd0
>>
>> 247,597 before and 429 after! WOW!
>>
>> Are virtual disks a problem with XFS? Why isn't this
>> memory allocation
>> deadlock issue more prevalent. I do see this article
>> mentioned on many
>> web posts. I don't specifically see any recommendation
>> to *not* use
>> XFS for the data domain though.
>>
>> I was running CentOS 7.3 on the file server, but before
>> rebooting the server,
>> I upgraded to the latest kernel and CentOS 7.4 in the
>> hopes that if there
>> was a kernel issue, that this would solve it.
>>
>> I took a few virtual systems down, and ran the defrag on
>> the disks. However,
>> with over 30 virtual systems, I don't really want to do
>> this individually.
>> I was wondering if I could run xfs_fsr on all the disks
>> LIVE? It says in the
>> manual that you can run it live, but I can't see how
>> this would be good when
>> a system is using that disk, and I don't want to deal
>> with major
>> corruption across the board. Any thoughts?
>>
>> Thanks,
>>
>> Jason.
>>
>> _______________________________________________
>> Users mailing list
>> Users(a)ovirt.org <mailto:Users@ovirt.org>
>> http://lists.ovirt.org/mailman/listinfo/users
>> <http://lists.ovirt.org/mailman/listinfo/users>
>>
>>
>
>
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<div class="moz-cite-prefix">On 10/02/2017 11:00 AM, Yaniv Kaul
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJgorsb2ctuEaTpNkzvixsDSjF-_ABH6JDMgw5X03WUgZgbo2A@mail.gmail.com">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Oct 2, 2017 at 5:57 PM, Jason
Keltz <span dir="ltr"><<a
href="mailto:jas@cse.yorku.ca"
target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><span
class=""> <br>
<div class="m_3456688468548054330moz-cite-prefix">On
10/02/2017 10:51 AM, Yaniv Kaul wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Oct 2, 2017 at
5:14 PM, Jason Keltz <span
dir="ltr"><<a
href="mailto:jas@cse.yorku.ca"
target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"><span>
<br>
<div
class="m_3456688468548054330m_-6564063642909371047moz-cite-prefix">On
10/02/2017 01:22 AM, Yaniv Kaul wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon,
Oct 2, 2017 at 5:11 AM, Jason
Keltz <span
dir="ltr"><<a
href="mailto:jas@cse.yorku.ca"
target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">Hi.<br>
<br>
For my data domain, I have one
NFS server with a large RAID
filesystem (9 TB).<br>
I'm only using 2 TB of that at
the moment. Today, my NFS
server hung with<br>
the following error:<br>
<br>
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
xfs: possible memory
allocation deadlock in
kmem_alloc<br>
</blockquote>
</blockquote>
<div><br>
</div>
<div>Can you share more of the
log so we'll see what happened
before and after?</div>
<div>Y.</div>
</div>
</div>
</div>
</blockquote>
</span><span class="">
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
Here is engine-log from
yesterday.. the problem
started around 14:29 PM.<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/engine-log.txt"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/10012017/engine-lo<wbr>g.txt</a><br>
<br>
Here is the vdsm log on one
of the virtualization hosts,
virt01:<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/vdsm.log.2"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/10012017/vdsm.log.<wbr>2</a><br>
<br>
Doing further investigation,
I found that the XFS error
messages didn't start
yesterday. You'll see they
started at the very end of
the day on September 23.
See:<br>
<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20170924"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/messages-20170924</a>
<br>
</div>
</blockquote>
<div><br>
</div>
<div>Our storage guys do NOT
think it's an XFS
fragmentation issue, but we'll
be looking at it.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span> Hmmm... almost sorry to hear that
because that would be easy to "fix"...
<br>
<span class=""> <br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
They continued on the 24th,
then on the 26th... I think
there were a few "hangs" on
those times that people were
complaining about, but we
didn't catch the problem.
However, the errors hit big
time yesterday at 14:27
PM... see here:<br>
<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20171001"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/messages-20171001</a><br>
<br>
If you want any other logs,
I'm happy to provide them.
I just don't know exactly
what to provide.<br>
<br>
Do you know if I can run the
XFS defrag command live?
Rather than on a disk by
disk, I'd rather just do it
on the whole filesystem.
There really aren't that
many files since it's just
ovirt disk images. However,
I don't understand the
implications to running
VMs. I wouldn't want to do
anything to create more
downtime.<br>
</div>
</blockquote>
<div><br>
</div>
<div>Should be enough to copy
the disks to make them less
fragmented.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span> Yes, but this requires downtime..
but there's plenty of additional storage,
so this would fix things well.</div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</span></div>
</blockquote>
<div><br>
</div>
<div>Live storage migration could be used.</div>
<div>Y.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><span
class=""><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
I had upgraded the engine server + 4
virtualization hosts from 4.1.1 to current
on September 20 along with upgrading them
from CentOS 7.3 to CentOS 7.4. virtfs,
the NFS file server, was running CentOS
7.3 and kernel
vmlinuz-3.10.0-514.16.1.el7.x8<wbr>6_64.
Only yesterday, did I upgrade it to CentOS
7.4 and hence kernel
vmlinuz-3.10.0-693.2.2.el7.x86<wbr>_64.<br>
<br>
I believe the problem is fully XFS
related, and not ovirt at all. Although,
I must admit, ovirt didn't help either.
When I rebooted the file server, the iso
and export domains were immediately
active, but the data domain took quite a
long time. I kept trying to activate it,
and it couldn't do it. I couldn't make a
host an SPM. I found that the data domain
directory on the virtualization host was a
"stale NFS file handle". I rebooted one
of the virtualization hosts (virt1), and
tried to make it the SPM. Again, it
wouldn't work. Finally, I ended up
turning everything into maintenance mode,
then activating just it, and I was able to
make it the SPM. I was then able to bring
everything up. I would have expected
ovirt to handle the problem a little more
gracefully, and give me more information
because I was sweating thinking I had to
restore all the VMs!<br>
</div>
</blockquote>
<div><br>
</div>
<div>Stale NFS is on our todo list to handle.
Quite challenging.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span> Thanks..<span class=""><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
I didn't think when I chose XFS as the
filesystem for my virtualization NFS
server that I would have to defragment the
filesystem manually. This is like the old
days of running Norton SpeedDisk to defrag
my 386...<br>
</div>
</blockquote>
<div><br>
</div>
<div>We are still not convinced it's an issue
- but we'll look into it (and perhaps ask
for more stats and data).</div>
</div>
</div>
</div>
</blockquote>
</span> Thanks!
<div>
<div class="h5"><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div>Y.</div>
<div> </div>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
Thanks for any help you can provide...<span
class="m_3456688468548054330HOEnZb"><font
color="#888888"><br>
<br>
Jason.</font></span>
<div>
<div
class="m_3456688468548054330h5"><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> </div>
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px
#ccc
solid;padding-left:1ex">
</blockquote>
<br>
All 4 virtualization hosts
of course had problems
since there was no<br>
longer any storage.<br>
<br>
In the end, it seems like
the problem is related to
XFS fragmentation...<br>
<br>
I read this great blog
here:<br>
<br>
<a
href="https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-deadlock-kmem_alloc/"
rel="noreferrer"
target="_blank"
moz-do-not-send="true">https://blog.codecentric.de/en<wbr>/2017/04/xfs-possible-memory-a<wbr>llocation-deadlock-kmem_alloc/</a><br>
<br>
In short, I tried this:<br>
<br>
# xfs_db -r -c "frag -f"
/dev/sdb1<br>
actual 4314253, ideal
43107, fragmentation
factor 99.00%<br>
<br>
Apparently the
fragmentation factor
doesn't mean much, but the
fact that<br>
"actual" number of extents
is considerably higher
than "ideal" extents seems
that it<br>
may be the problem.<br>
<br>
I saw that many of my
virtual disks that are
written to a lot have, of
course,<br>
a lot of extents...<br>
<br>
For example, on our main
web server disk image,
there were 247,597<br>
extents alone! I took the
web server down, and ran
the XFS defrag<br>
command on the disk...<br>
<br>
# xfs_fsr -v
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
extents before:247597
after:429 DONE
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
<br>
247,597 before and 429
after! WOW!<br>
<br>
Are virtual disks a
problem with XFS? Why
isn't this memory
allocation<br>
deadlock issue more
prevalent. I do see this
article mentioned on many<br>
web posts. I don't
specifically see any
recommendation to *not*
use<br>
XFS for the data domain
though.<br>
<br>
I was running CentOS 7.3
on the file server, but
before rebooting the
server,<br>
I upgraded to the latest
kernel and CentOS 7.4 in
the hopes that if there<br>
was a kernel issue, that
this would solve it.<br>
<br>
I took a few virtual
systems down, and ran the
defrag on the disks.
However,<br>
with over 30 virtual
systems, I don't really
want to do this
individually.<br>
I was wondering if I could
run xfs_fsr on all the
disks LIVE? It says in
the<br>
manual that you can run it
live, but I can't see how
this would be good when<br>
a system is using that
disk, and I don't want to
deal with major<br>
corruption across the
board. Any thoughts?<br>
<br>
Thanks,<br>
<br>
Jason.<br>
<br>
______________________________<wbr>_________________<br>
Users mailing list<br>
<a
href="mailto:Users@ovirt.org"
target="_blank"
moz-do-not-send="true">Users(a)ovirt.org</a><br>
<a
href="http://lists.ovirt.org/mailman/listinfo/users"
rel="noreferrer"
target="_blank"
moz-do-not-send="true">http://lists.ovirt.org/mailman<wbr...
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
</div>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
</div>
</div>
</div>
</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
<br>
</body>
</html>
--------------8888294F2C8EF5B404842160--
11:06 a.m.
New subject: xfs fragmentation problem caused data domain to hang
This is a multi-part message in MIME format.
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On 10/02/2017 11:05 AM, Jason Keltz wrote:
On 10/02/2017 11:00 AM, Yaniv Kaul wrote:
>
>
> On Mon, Oct 2, 2017 at 5:57 PM, Jason Keltz <jas(a)cse.yorku.ca
> <mailto:jas@cse.yorku.ca>> wrote:
>
>
> On 10/02/2017 10:51 AM, Yaniv Kaul wrote:
>>
>>
>> On Mon, Oct 2, 2017 at 5:14 PM, Jason Keltz <jas(a)cse.yorku.ca
>> <mailto:jas@cse.yorku.ca>> wrote:
>>
>>
>> On 10/02/2017 01:22 AM, Yaniv Kaul wrote:
>>>
>>>
>>> On Mon, Oct 2, 2017 at 5:11 AM, Jason Keltz
>>> <jas(a)cse.yorku.ca <mailto:jas@cse.yorku.ca>> wrote:
>>>
>>> Hi.
>>>
>>> For my data domain, I have one NFS server with a large
>>> RAID filesystem (9 TB).
>>> I'm only using 2 TB of that at the moment. Today, my
>>> NFS server hung with
>>> the following error:
>>>
>>> xfs: possible memory allocation deadlock in kmem_alloc
>>>
>>>
>>> Can you share more of the log so we'll see what happened
>>> before and after?
>>> Y.
>>>
>>>
>>> Here is engine-log from yesterday.. the problem started
>>> around 14:29 PM.
>>>
http://www.eecs.yorku.ca/~jas/ovirt-debug/10012017/engine-log.txt
>>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/engine-log.txt>
>>>
>>> Here is the vdsm log on one of the virtualization
>>> hosts, virt01:
>>> http://www.eecs.yorku.ca/~jas/ovirt-debug/10012017/vdsm.log.2
>>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/vdsm.log.2>
>>>
>>> Doing further investigation, I found that the XFS error
>>> messages didn't start yesterday. You'll see they
>>> started at the very end of the day on September 23. See:
>>>
>>> http://www.eecs.yorku.ca/~jas/ovirt-debug/messages-20170924
>>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20170924>
>>>
>>>
>>>
>>> Our storage guys do NOT think it's an XFS fragmentation
>>> issue, but we'll be looking at it.
>>
This is an interesting thread to read because the problem sounds quite
similar:
http://oss.sgi.com/archives/xfs/2016-03/msg00447.html
In particular, quoted from that:
XFS maintains the full extent list for an active inode in memory,
As it is, yes, the memory allocation problem is with the in-core
extent tree, and we've known about it for some time. The issue is
that as memory gets fragmented, the top level indirection array
grows too large to be allocated as a contiguous chunk. When this
happens really depends on memory load, uptime and the way the extent
tree is being modified.
So in my case, I have a bunch of big XFS disk images for virtual disks.
As the files are big with many extents, keeping all that information in
memory at the same time may be the culprit. Having many extents per se
isn't the problem, but having enough memory to be able to store all the
information simultaneously may be. Possible solutions would be to
increase the default extent size of the volume (which I'm not sure how
to do), defragment the disk, and hence less extents, or potentially add
more memory to the file server. It has 64G.
>> Hmmm... almost sorry to hear that because that would
be easy
>> to "fix"...
>>
>>>
>>> They continued on the 24th, then on the 26th... I think
>>> there were a few "hangs" on those times that people
>>> were complaining about, but we didn't catch the
>>> problem. However, the errors hit big time yesterday at
>>> 14:27 PM... see here:
>>>
>>> http://www.eecs.yorku.ca/~jas/ovirt-debug/messages-20171001
>>>
<http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20171001>
>>>
>>> If you want any other logs, I'm happy to provide them.
>>> I just don't know exactly what to provide.
>>>
>>> Do you know if I can run the XFS defrag command live?
>>> Rather than on a disk by disk, I'd rather just do it on
>>> the whole filesystem. There really aren't that many
>>> files since it's just ovirt disk images. However, I
>>> don't understand the implications to running VMs. I
>>> wouldn't want to do anything to create more downtime.
>>>
>>>
>>> Should be enough to copy the disks to make them less
>>> fragmented.
>> Yes, but this requires downtime.. but there's plenty of
>> additional storage, so this would fix things well.
>>
>
> Live storage migration could be used.
> Y.
>
>
>
>>
>> I had upgraded the engine server + 4 virtualization hosts
>> from 4.1.1 to current on September 20 along with upgrading
>> them from CentOS 7.3 to CentOS 7.4. virtfs, the NFS file
>> server, was running CentOS 7.3 and kernel
>> vmlinuz-3.10.0-514.16.1.el7.x86_64. Only yesterday, did I
>> upgrade it to CentOS 7.4 and hence kernel
>> vmlinuz-3.10.0-693.2.2.el7.x86_64.
>>
>> I believe the problem is fully XFS related, and not ovirt at
>> all. Although, I must admit, ovirt didn't help either. When
>> I rebooted the file server, the iso and export domains were
>> immediately active, but the data domain took quite a long
>> time. I kept trying to activate it, and it couldn't do it.
>> I couldn't make a host an SPM. I found that the data domain
>> directory on the virtualization host was a "stale NFS file
>> handle". I rebooted one of the virtualization hosts
>> (virt1), and tried to make it the SPM. Again, it wouldn't
>> work. Finally, I ended up turning everything into
>> maintenance mode, then activating just it, and I was able to
>> make it the SPM. I was then able to bring everything up. I
>> would have expected ovirt to handle the problem a little
>> more gracefully, and give me more information because I was
>> sweating thinking I had to restore all the VMs!
>>
>>
>> Stale NFS is on our todo list to handle. Quite challenging.
> Thanks..
>
>>
>> I didn't think when I chose XFS as the filesystem for my
>> virtualization NFS server that I would have to defragment
>> the filesystem manually. This is like the old days of
>> running Norton SpeedDisk to defrag my 386...
>>
>>
>> We are still not convinced it's an issue - but we'll look into
>> it (and perhaps ask for more stats and data).
> Thanks!
>
>
>> Y.
>>
>>
>> Thanks for any help you can provide...
>>
>> Jason.
>>
>>
>>>
>>> All 4 virtualization hosts of course had problems since
>>> there was no
>>> longer any storage.
>>>
>>> In the end, it seems like the problem is related to XFS
>>> fragmentation...
>>>
>>> I read this great blog here:
>>>
>>>
https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-dea...
>>>
<https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-dea...
>>>
>>> In short, I tried this:
>>>
>>> # xfs_db -r -c "frag -f" /dev/sdb1
>>> actual 4314253, ideal 43107, fragmentation factor 99.00%
>>>
>>> Apparently the fragmentation factor doesn't mean much,
>>> but the fact that
>>> "actual" number of extents is considerably higher than
>>> "ideal" extents seems that it
>>> may be the problem.
>>>
>>> I saw that many of my virtual disks that are written to
>>> a lot have, of course,
>>> a lot of extents...
>>>
>>> For example, on our main web server disk image, there
>>> were 247,597
>>> extents alone! I took the web server down, and ran the
>>> XFS defrag
>>> command on the disk...
>>>
>>> # xfs_fsr -v 9a634692-1302-471f-a92e-c978b2b67fd0
>>> 9a634692-1302-471f-a92e-c978b2b67fd0
>>> extents before:247597 after:429 DONE
>>> 9a634692-1302-471f-a92e-c978b2b67fd0
>>>
>>> 247,597 before and 429 after! WOW!
>>>
>>> Are virtual disks a problem with XFS? Why isn't this
>>> memory allocation
>>> deadlock issue more prevalent. I do see this article
>>> mentioned on many
>>> web posts. I don't specifically see any recommendation
>>> to *not* use
>>> XFS for the data domain though.
>>>
>>> I was running CentOS 7.3 on the file server, but before
>>> rebooting the server,
>>> I upgraded to the latest kernel and CentOS 7.4 in the
>>> hopes that if there
>>> was a kernel issue, that this would solve it.
>>>
>>> I took a few virtual systems down, and ran the defrag
>>> on the disks. However,
>>> with over 30 virtual systems, I don't really want to do
>>> this individually.
>>> I was wondering if I could run xfs_fsr on all the disks
>>> LIVE? It says in the
>>> manual that you can run it live, but I can't see how
>>> this would be good when
>>> a system is using that disk, and I don't want to deal
>>> with major
>>> corruption across the board. Any thoughts?
>>>
>>> Thanks,
>>>
>>> Jason.
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users(a)ovirt.org <mailto:Users@ovirt.org>
>>> http://lists.ovirt.org/mailman/listinfo/users
>>> <http://lists.ovirt.org/mailman/listinfo/users>
>>>
>>>
>>
>>
>
>
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
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<br>
<div class="moz-cite-prefix">On 10/02/2017 11:05 AM, Jason Keltz
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:b3e2ab23-7bab-ddc2-e230-a650f87a1773@cse.yorku.ca">
<meta http-equiv="Content-Type" content="text/html;
charset=utf-8">
<div class="moz-cite-prefix">On 10/02/2017 11:00 AM, Yaniv Kaul
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJgorsb2ctuEaTpNkzvixsDSjF-_ABH6JDMgw5X03WUgZgbo2A@mail.gmail.com">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Oct 2, 2017 at 5:57 PM,
Jason Keltz <span dir="ltr"><<a
href="mailto:jas@cse.yorku.ca" target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><span
class=""> <br>
<div class="m_3456688468548054330moz-cite-prefix">On
10/02/2017 10:51 AM, Yaniv Kaul wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Oct 2, 2017
at 5:14 PM, Jason Keltz <span
dir="ltr"><<a
href="mailto:jas@cse.yorku.ca"
target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"><span>
<br>
<div
class="m_3456688468548054330m_-6564063642909371047moz-cite-prefix">On
10/02/2017 01:22 AM, Yaniv Kaul
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon,
Oct 2, 2017 at 5:11 AM, Jason
Keltz <span
dir="ltr"><<a
href="mailto:jas@cse.yorku.ca" target="_blank"
moz-do-not-send="true">jas(a)cse.yorku.ca</a>&gt;</span>
wrote:<br>
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">Hi.<br>
<br>
For my data domain, I have
one NFS server with a large
RAID filesystem (9 TB).<br>
I'm only using 2 TB of that
at the moment. Today, my NFS
server hung with<br>
the following error:<br>
<br>
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
xfs: possible memory
allocation deadlock in
kmem_alloc<br>
</blockquote>
</blockquote>
<div><br>
</div>
<div>Can you share more of the
log so we'll see what
happened before and after?</div>
<div>Y.</div>
</div>
</div>
</div>
</blockquote>
</span><span class="">
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
Here is engine-log from
yesterday.. the problem
started around 14:29 PM.<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/engine-log.txt"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/10012017/engine-lo<wbr>g.txt</a><br>
<br>
Here is the vdsm log on
one of the virtualization
hosts, virt01:<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/10012017/vdsm.log.2"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/10012017/vdsm.log.<wbr>2</a><br>
<br>
Doing further
investigation, I found
that the XFS error
messages didn't start
yesterday. You'll see
they started at the very
end of the day on
September 23. See:<br>
<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20170924"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/messages-20170924</a>
<br>
</div>
</blockquote>
<div><br>
</div>
<div>Our storage guys do NOT
think it's an XFS
fragmentation issue, but
we'll be looking at it.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span></div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</span></div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</blockquote>
This is an interesting thread to read because the problem sounds
quite similar:<br>
<br>
<a class="moz-txt-link-freetext"
href="http://oss.sgi.com/archives/xfs/2016-03/msg00447.html">...
<br>
In particular, quoted from that:<br>
<blockquote type="cite">
<pre>XFS maintains the full extent list for an active inode in
memory,</pre>
</blockquote>
<blockquote type="cite">
<pre>As it is, yes, the memory allocation problem is with the in-core
extent tree, and we've known about it for some time. The issue is
that as memory gets fragmented, the top level indirection array
grows too large to be allocated as a contiguous chunk. When this
happens really depends on memory load, uptime and the way the extent
tree is being modified.
</pre>
</blockquote>
<br>
So in my case, I have a bunch of big XFS disk images for virtual
disks. As the files are big with many extents, keeping all that
information in memory at the same time may be the culprit. Having
many extents per se isn't the problem, but having enough memory to
be able to store all the information simultaneously may be.
Possible solutions would be to increase the default extent size of
the volume (which I'm not sure how to do), defragment the disk, and
hence less extents, or potentially add more memory to the file
server. It has 64G. <br>
<br>
<blockquote type="cite"
cite="mid:b3e2ab23-7bab-ddc2-e230-a650f87a1773@cse.yorku.ca">
<blockquote type="cite"
cite="mid:CAJgorsb2ctuEaTpNkzvixsDSjF-_ABH6JDMgw5X03WUgZgbo2A@mail.gmail.com">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><span
class="">
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"><span
class="">
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
</div>
</div>
</div>
</blockquote>
</span> Hmmm... almost sorry to hear
that because that would be easy to
"fix"... <br>
<span class=""> <br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
They continued on the
24th, then on the 26th...
I think there were a few
"hangs" on those times
that people were
complaining about, but we
didn't catch the problem.
However, the errors hit
big time yesterday at
14:27 PM... see here:<br>
<br>
<a
class="m_3456688468548054330m_-6564063642909371047moz-txt-link-freetext"
href="http://www.eecs.yorku.ca/%7Ejas/ovirt-debug/messages-20171001"
target="_blank"
moz-do-not-send="true">http://www.eecs.yorku.ca/~jas/<wbr>ovirt-debug/messages-20171001</a><br>
<br>
If you want any other
logs, I'm happy to provide
them. I just don't know
exactly what to provide.<br>
<br>
Do you know if I can run
the XFS defrag command
live? Rather than on a
disk by disk, I'd rather
just do it on the whole
filesystem. There really
aren't that many files
since it's just ovirt disk
images. However, I don't
understand the
implications to running
VMs. I wouldn't want to
do anything to create more
downtime.<br>
</div>
</blockquote>
<div><br>
</div>
<div>Should be enough to copy
the disks to make them less
fragmented.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span> Yes, but this requires
downtime.. but there's plenty of
additional storage, so this would fix
things well.</div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</span></div>
</blockquote>
<div><br>
</div>
<div>Live storage migration could be used.</div>
<div>Y.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF"><span
class=""><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
I had upgraded the engine server + 4
virtualization hosts from 4.1.1 to
current on September 20 along with
upgrading them from CentOS 7.3 to CentOS
7.4. virtfs, the NFS file server, was
running CentOS 7.3 and kernel
vmlinuz-3.10.0-514.16.1.el7.x8<wbr>6_64.
Only yesterday, did I upgrade it to
CentOS 7.4 and hence kernel
vmlinuz-3.10.0-693.2.2.el7.x86<wbr>_64.<br>
<br>
I believe the problem is fully XFS
related, and not ovirt at all.
Although, I must admit, ovirt didn't
help either. When I rebooted the file
server, the iso and export domains were
immediately active, but the data domain
took quite a long time. I kept trying
to activate it, and it couldn't do it.
I couldn't make a host an SPM. I found
that the data domain directory on the
virtualization host was a "stale NFS
file handle". I rebooted one of the
virtualization hosts (virt1), and tried
to make it the SPM. Again, it wouldn't
work. Finally, I ended up turning
everything into maintenance mode, then
activating just it, and I was able to
make it the SPM. I was then able to
bring everything up. I would have
expected ovirt to handle the problem a
little more gracefully, and give me more
information because I was sweating
thinking I had to restore all the VMs!<br>
</div>
</blockquote>
<div><br>
</div>
<div>Stale NFS is on our todo list to
handle. Quite challenging.</div>
<div> </div>
</div>
</div>
</div>
</blockquote>
</span> Thanks..<span class=""><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
I didn't think when I chose XFS as the
filesystem for my virtualization NFS
server that I would have to defragment
the filesystem manually. This is like
the old days of running Norton SpeedDisk
to defrag my 386...<br>
</div>
</blockquote>
<div><br>
</div>
<div>We are still not convinced it's an
issue - but we'll look into it (and
perhaps ask for more stats and data).</div>
</div>
</div>
</div>
</blockquote>
</span> Thanks!
<div>
<div class="h5"><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div>Y.</div>
<div> </div>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div text="#000000"
bgcolor="#FFFFFF"> <br>
Thanks for any help you can provide...<span
class="m_3456688468548054330HOEnZb"><font
color="#888888"><br>
<br>
Jason.</font></span>
<div>
<div
class="m_3456688468548054330h5"><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> </div>
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px
#ccc
solid;padding-left:1ex">
<blockquote
class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px
#ccc
solid;padding-left:1ex">
</blockquote>
<br>
All 4 virtualization
hosts of course had
problems since there was
no<br>
longer any storage.<br>
<br>
In the end, it seems
like the problem is
related to XFS
fragmentation...<br>
<br>
I read this great blog
here:<br>
<br>
<a
href="https://blog.codecentric.de/en/2017/04/xfs-possible-memory-allocation-deadlock-kmem_alloc/"
rel="noreferrer"
target="_blank"
moz-do-not-send="true">https://blog.codecentric.de/en<wbr>/2017/04/xfs-possible-memory-a<wbr>llocation-deadlock-kmem_alloc/</a><br>
<br>
In short, I tried this:<br>
<br>
# xfs_db -r -c "frag -f"
/dev/sdb1<br>
actual 4314253, ideal
43107, fragmentation
factor 99.00%<br>
<br>
Apparently the
fragmentation factor
doesn't mean much, but
the fact that<br>
"actual" number of
extents is considerably
higher than "ideal"
extents seems that it<br>
may be the problem.<br>
<br>
I saw that many of my
virtual disks that are
written to a lot have,
of course,<br>
a lot of extents...<br>
<br>
For example, on our main
web server disk image,
there were 247,597<br>
extents alone! I took
the web server down, and
ran the XFS defrag<br>
command on the disk...<br>
<br>
# xfs_fsr -v
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
extents before:247597
after:429 DONE
9a634692-1302-471f-a92e-c978b2<wbr>b67fd0<br>
<br>
247,597 before and 429
after! WOW!<br>
<br>
Are virtual disks a
problem with XFS? Why
isn't this memory
allocation<br>
deadlock issue more
prevalent. I do see
this article mentioned
on many<br>
web posts. I don't
specifically see any
recommendation to *not*
use<br>
XFS for the data domain
though.<br>
<br>
I was running CentOS 7.3
on the file server, but
before rebooting the
server,<br>
I upgraded to the latest
kernel and CentOS 7.4 in
the hopes that if there<br>
was a kernel issue, that
this would solve it.<br>
<br>
I took a few virtual
systems down, and ran
the defrag on the
disks. However,<br>
with over 30 virtual
systems, I don't really
want to do this
individually.<br>
I was wondering if I
could run xfs_fsr on all
the disks LIVE? It says
in the<br>
manual that you can run
it live, but I can't see
how this would be good
when<br>
a system is using that
disk, and I don't want
to deal with major<br>
corruption across the
board. Any thoughts?<br>
<br>
Thanks,<br>
<br>
Jason.<br>
<br>
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Jason Keltz