2:14 a.m.
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----- Original Message -----
From: "Alan Johnson" <alan(a)datdec.com>
To: "users" <users(a)ovirt.org>
Sent: Wednesday, September 18, 2013 3:47:08 AM
Subject: [Users] convert thin provisioned disks to preallocated
I am pretty sure I know the answer, but is there any way to do this
gracefully, i.e. within the confines of the oVirt API? This is on an iSCSI
storage domain. My understanding and further research suggest no, but I
wanted to ask before we endeavor on a major overhaul of a production system
that some one setup without knowing the better of to the 2 for such use.
I am very familiar with the underlying systems (LVM, KVM, etc.) and
would
appreciate any suggested hacks. So far, here is what I have come up with:
Sure to work: Setup a new VM with preallocated drives. Boot both VMs
off of a
live virtual CD. Use cat/pv and nc (netcat) to read directly from the block
devices on one and write directly to the block devices on the other. Reboot
the new VM from the internal disks. Tweak MAC addresses along the way so the
new VM gets those of the old. The down side is the down time, but we can
probably swallow it if we have to. Any other risks?
Might work: Create a new VM. Identify the logical volumes (LVs) are
assigned
for that block devices used by the new and the old. Log into the SPM and
read directly from the old LVs to the new. This is similar to that above,
but I expect I need to run the data through some kind of qcow2-to-raw
conversion process to make this work. Similar down sides to the above, but
maybe less so? Thoughts?
Another thought I had was to just write zeros to the empty space on
the block
devices, from inside the guest OS, until the full allocation is achieved.
The down side is potential impact on performance of the system while it is
filling up and for the (hopefully) very short time the file system is full
before an rm of the zeros file kicks in. Also we would still have qcow2
underneath, so would it still add overhead, or does that only apply when it
grows? Any other down sides to this?
Thanks in advance for your thoughts and consideration.
i guess that using ovirt api you can export the vm, and import back changing the
allocation policy of the disks..
need to verify this though.
________________
Alan Johnson
alan(a)datdec.com
Date Format PSA
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
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<html><body><div style=3D"font-family: times new roman, new york,
times, se=
rif; font-size: 12pt; color:
#000000"><div><br></div><div><br></div><hr
id=
=3D"zwchr"><blockquote style=3D"border-left:2px solid
#1010FF;margin-left:5=
px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-de=
coration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>Fr=
om: </b>"Alan Johnson"
&lt;alan(a)datdec.com&gt;<br><b>To: </b>"users"
<us=
ers(a)ovirt.org&gt;<br><b>Sent: </b>Wednesday, September 18, 2013
3:47:08 AM<=
br><b>Subject: </b>[Users] convert thin provisioned disks to
preallocated<b=
r><div><br></div><div dir=3D"ltr"><div
class=3D"gmail_default" style=3D"fon=
t-family:verdana,sans-serif">I am pretty sure I know the answer, but is the=
re any way to do this gracefully, i.e. within the confines of the oVirt API=
? This is on an iSCSI storage domain. My understanding and furt=
her research suggest no, but I wanted to ask before we endeavor on a major =
overhaul of a production system that some one setup without knowing the bet=
ter of to the 2 for such use.</div><div class=3D"gmail_default"
style=3D"fo=
nt-family:verdana,sans-serif"><br></div><div
class=3D"gmail_default" style=
=3D"font-family:verdana,sans-serif">I am very familiar with the underlying =
systems (LVM, KVM, etc.) and would appreciate any suggested hacks. So=
far, here is what I have come up with:<br></div><div
class=3D"gmail_defaul=
t"
style=3D"font-family:verdana,sans-serif"><br></div><div
class=3D"gmail_d=
efault" style=3D"font-family:verdana,sans-serif">Sure to work: Setup a
new =
VM with preallocated drives. Boot both VMs off of a live virtual CD. =
Use cat/pv and nc (netcat) to read directly from the block devices on=
one and write directly to the block devices on the other. Reboot the=
new VM from the internal disks. Tweak MAC addresses along the way so the n=
ew VM gets those of the old. The down side is the down time, but we c=
an probably swallow it if we have to. Any other risks?</div><div clas=
s=3D"gmail_default"
style=3D"font-family:verdana,sans-serif"><br></div><div=
class=3D"gmail_default"
style=3D"font-family:verdana,sans-serif">Might wor=
k: Create a new VM. Identify the logical volumes (LVs) are assigned f=
or that block devices used by the new and the old. Log into the SPM a=
nd read directly from the old LVs to the new. This is similar to that=
above, but I expect I need to run the data through some kind of qcow2-to-r=
aw conversion process to make this work. Similar down sides to the ab=
ove, but maybe less so? Thoughts?</div><div
class=3D"gmail_default" s=
tyle=3D"font-family:verdana,sans-serif"><br></div><div
class=3D"gmail_defau=
lt" style=3D"font-family:verdana,sans-serif">Another thought I had was
to j=
ust write zeros to the empty space on the block devices, from inside the gu=
est OS, until the full allocation is achieved. The down side is poten=
tial impact on performance of the system while it is filling up and for the=
(hopefully) very short time the file system is full before an rm of the ze=
ros file kicks in. Also we would still have qcow2 underneath, so woul=
d it still add overhead, or does that only apply when it grows? Any o=
ther down sides to this?</div><div class=3D"gmail_default"
style=3D"font-fa=
mily:verdana,sans-serif"><br></div><div
class=3D"gmail_default" style=3D"fo=
nt-family:verdana,sans-serif">Thanks in advance for your thoughts and consi=
deration.</div></div></blockquote><div>i guess that using ovirt
api you can=
export the vm, and import back changing the allocation policy of the disks=
..<br></div><div>need to verify this
though.<br></div><blockquote style=3D"=
border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;f=
ont-weight:normal;font-style:normal;text-decoration:none;font-family:Helvet=
ica,Arial,sans-serif;font-size:12pt;"><div dir=3D"ltr"><div
class=3D"gmail_=
default"
style=3D"font-family:verdana,sans-serif"><br></div><div><span
styl=
e=3D"font-family: verdana,sans-serif;" data-mce-style=3D"font-family:
verda=
na,sans-serif;" face=3D"verdana,
sans-serif">________________<br>Alan Johns=
on<br><a href=3D"mailto:alan@datdec.com"
target=3D"_blank">alan(a)datdec.com<=
/a></span><div><span
style=3D"font-size:16px;font-variant:small-caps;text-a=
lign:center;background-color:rgb(255,255,255)"><a
href=3D"http://xkcd.com/1=
179/" target=3D"_blank"><span style=3D"font-family:
verdana,sans-serif;" da=
ta-mce-style=3D"font-family: verdana,sans-serif;" face=3D"verdana,
sans-ser=
if">Date Format PSA</span></a></span><br
data-mce-bogus=3D"1"></div></div><=
/div><br>_______________________________________________<br>Users mailing
l=
ist<br>Users@ovirt.org<br>http://lists.ovirt.org/mailman/listinfo/users<br>=
</blockquote><div><br></div></div></body></html>
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