5:08 a.m.
Hi!
In some setups, like when you got two datacenters that works like failover sites, you
would like to have two external raid controllers(storage devices), one in each
datacenter.
You then send two identical LUN's, from each controller, to a cluster, let's say
two hosts, for simplicity. What you normally do is to host raid these LUN's in
mirror(raid 1), so the hosts write the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management? Because if I
can't, it will be a problem, because if I host raid at the host level, then the
storage would be local storage for oVirt, wouldn't it? And then I suppose it can't
be used for live migration, can it?
Regrds Johan
6:55 a.m.
You can use replicated at the SAN level storage between different DCs, for DR. You can
also use Gluster for the same purpose.
Setting RAID1 between two geographically separate hosts is asking for trouble.
----- Original Message -----
From: "Johan Kragsterman"
<johan.kragsterman(a)capvert.se>
To: users(a)ovirt.org
Sent: Sunday, 29 July, 2012 12:08:20 PM
Subject: [Users] host raiding two LUN from different external storage
Hi!
In some setups, like when you got two datacenters that works like
failover sites, you would like to have two external raid
controllers(storage devices), one in each datacenter.
You then send two identical LUN's, from each controller, to a
cluster, let's say two hosts, for simplicity. What you normally do
is to host raid these LUN's in mirror(raid 1), so the hosts write
the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management?
Because if I can't, it will be a problem, because if I host raid at
the host level, then the storage would be local storage for oVirt,
wouldn't it? And then I suppose it can't be used for live migration,
can it?
Regrds Johan
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
2:02 a.m.
Hi!
Of coarse you can use this feature at the SAN level, if you got it. I can do it in my
setup, but there are other complications with doing so, as well, as performance issues.
Continues/direct/syncronous replication, whatever you want to call it, is a performance
demanding operation, and your SAN controllers need to be able to put up with it, as well
as your interconnection needs to be good.
If you use fibre channel, and you got a proper connection, I can see no reason why you
shouldn't do it? The difference in latency will be minimal, if you don't have the
two DC's too far apart. And if you use LVM for mirroring, the second node(host) will
detect the LVM metadata by itself, so you don't have to perform the mirror operation
on the second node.
I wouldn't do it with iScsi though, and/or over an interconnection that you don't
control yourself.
A drawback might be, though, that the data is on a logical volume on the host level, and
not on the LUN, which means that you need backup on the host level.
Rgrds Johan
-----users-bounces(a)ovirt.org skrev: -----
Till: Johan Kragsterman <johan.kragsterman(a)capvert.se>
Från: Dan Yasny
Sänt av: users-bounces(a)ovirt.org
Datum: 2012.07.29 12:56
Kopia: users(a)ovirt.org
Ärende: Re: [Users] host raiding two LUN from different external storage
You can use replicated at the SAN level storage between different DCs, for DR. You can
also use Gluster for the same purpose.
Setting RAID1 between two geographically separate hosts is asking for trouble.
----- Original Message -----
From: "Johan Kragsterman"
<johan.kragsterman(a)capvert.se>
To: users(a)ovirt.org
Sent: Sunday, 29 July, 2012 12:08:20 PM
Subject: [Users] host raiding two LUN from different external storage
Hi!
In some setups, like when you got two datacenters that works like
failover sites, you would like to have two external raid
controllers(storage devices), one in each datacenter.
You then send two identical LUN's, from each controller, to a
cluster, let's say two hosts, for simplicity. What you normally do
is to host raid these LUN's in mirror(raid 1), so the hosts write
the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management?
Because if I can't, it will be a problem, because if I host raid at
the host level, then the storage would be local storage for oVirt,
wouldn't it? And then I suppose it can't be used for live migration,
can it?
Regrds Johan
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
1:12 a.m.
Hi!
Dan, it seems you know something about storage, so I adress you:
I find the oVirt storage framework a bit odd. It has it advantages, but also a lot of
disadvantiages, it seems.
I did earlier, in this thread, ask about storage setups you want to use in enterprise
environments. And I like to continue that discussion.
If you like to replicate on SAN level between, let's say two different LUN's, that
should contain the same informnation for a host, or for a VM, then you end up in trouble
if you use the oVirt storage system. Because you need to put the two LUN's from the
different datacenters together, to become ONE unit, otherwise you don't get the right
uuid for live migration. Isn't right?
As you wrote earlier, this might be solved with gluster, but is it so, that oVirt is going
to get enterprise features only in pair with gluster? I don't believe that is a good
idea for the adoption of oVirt.
oVirt must have a good support for enterprise features that is used today, like NPIV. I
have googled around oVirt and NPIV and didn't come up with much, you can tell me
something about it?
I belive it would be good if oVirt supported other storage system types than the one
system it supports today, that all storage should be imported and handled by LVM and oVirt
engine.
Most enterprise storage today is fibre channel and NPIV based. You boot most the VM's
through NPIV LUN's, you add more space through thin provisioning or more NPIV
LUN's.
And this is going to continue, even if the Fc world move to FCoE.
So perhaps you can tell me a little bit about the storage strategy that oVirt dev team
has?
Rgrds Johan
-----Dan Yasny <dyasny(a)redhat.com> skrev: -----
Till: Johan Kragsterman <johan.kragsterman(a)capvert.se>
Från: Dan Yasny <dyasny(a)redhat.com>
Datum: 2012.07.29 12:55
Kopia: users(a)ovirt.org
Ärende: Re: [Users] host raiding two LUN from different external storage
You can use replicated at the SAN level storage between different DCs, for DR. You can
also use Gluster for the same purpose.
Setting RAID1 between two geographically separate hosts is asking for trouble.
----- Original Message -----
From: "Johan Kragsterman"
<johan.kragsterman(a)capvert.se>
To: users(a)ovirt.org
Sent: Sunday, 29 July, 2012 12:08:20 PM
Subject: [Users] host raiding two LUN from different external storage
Hi!
In some setups, like when you got two datacenters that works like
failover sites, you would like to have two external raid
controllers(storage devices), one in each datacenter.
You then send two identical LUN's, from each controller, to a
cluster, let's say two hosts, for simplicity. What you normally do
is to host raid these LUN's in mirror(raid 1), so the hosts write
the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management?
Because if I can't, it will be a problem, because if I host raid at
the host level, then the storage would be local storage for oVirt,
wouldn't it? And then I suppose it can't be used for live migration,
can it?
Regrds Johan
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
3:19 a.m.
----- Original Message -----
From: "Johan Kragsterman"
<johan.kragsterman(a)capvert.se>
To: "Dan Yasny" <dyasny(a)redhat.com>
Cc: users(a)ovirt.org
Sent: Thursday, 2 August, 2012 8:12:45 AM
Subject: Re: [Users] host raiding two LUN from different external storage
Hi!
Dan, it seems you know something about storage, so I adress you:
I find the oVirt storage framework a bit odd. It has it advantages,
but also a lot of disadvantiages, it seems.
I did earlier, in this thread, ask about storage setups you want to
use in enterprise environments. And I like to continue that
discussion.
If you like to replicate on SAN level between, let's say two
different LUN's, that should contain the same informnation for a
host, or for a VM, then you end up in trouble if you use the oVirt
storage system. Because you need to put the two LUN's from the
different datacenters together, to become ONE unit, otherwise you
don't get the right uuid for live migration. Isn't right?
If you are using SAN level replication, it is not an active/active replication. The second
replica is in standby, and if the first LUN fails, you can substitute with the replica (of
course you can have corruption that gets replicated and then the storage is gone. RAID is
never a substitution for backups).
With oVirt, if you have an offsite LUN replica, for DR reasons, you can take that LUN and
attach to an offsite replica of the oVirt setup (engine plus hosts) - and the original
storage domain will be right there for you to use. Once the DR setup is operational, VMs
can live migrate within it.
As you wrote earlier, this might be solved with gluster, but is it
so, that oVirt is going to get enterprise features only in pair with
gluster? I don't believe that is a good idea for the adoption of
oVirt.
Gluster has the replication feature built in. So do most enterprise grade storage
solutions. If your SAN supports LUN replication, this feature can be used with oVirt or
any other system that keeps data on the LUN, no special magic there.
oVirt must have a good support for enterprise features that is used
today, like NPIV. I have googled around oVirt and NPIV and didn't
come up with much, you can tell me something about it?
NPIV is completely out of context here. Generally speaking, Linux supports NPIV (see
http://fedoraproject.org/wiki/Features/VirtStorageManagement) so if you handle the actual
commands, and oVirt hosts see the LUNs in dev/mapper it will work. In very broad terms of
course, oVirt does not care how device-mapper gets to see the LUNs, if they are visible,
normally, they can be used.
If you are talking about incorporating NPIV settings in oVirt engine host management, then
it's a feature that needs to be spec'd out in the oVirt wiki first, and since
it's an open project, anyone willing to actually develop it is welcome to contribute.
I belive it would be good if oVirt supported other storage system
types than the one system it supports today, that all storage should
be imported and handled by LVM and oVirt engine.
You mean clustered filesystems? We already support those, look at PosixFS.
But still, LVM provides a huge advantage over a classical clustered FS - less overhead,
simple management using standard Linux commands, amazing scalability (what other
virtualization solution scales to hundreds of hosts out of the box?)
Most enterprise storage today is fibre channel and NPIV based. You
boot most the VM's through NPIV LUN's, you add more space through
thin provisioning or more NPIV LUN's.
And this is going to continue, even if the Fc world move to FCoE.
Actually, I haven't seen NPIV used too much, normally, when you have an FC
infrastructure in place, purchasing an extra port/HBA is not an issue, and it's so
much easier to manage without virtualizing - plug your cables in, set up zones, and
you're good to go.
So I don't agree about "most", but as I said before, if you want to use
NPIV, you can, oVirt will simply not manage it for you, at least not in the current
version.
So perhaps you can tell me a little bit about the storage strategy
that oVirt dev team has?
Everything is in the wiki - read the storage related feature pages. And if you want to
pitch in, you are always welcome to
Rgrds Johan
-----Dan Yasny <dyasny(a)redhat.com> skrev: -----
Till: Johan Kragsterman <johan.kragsterman(a)capvert.se>
Från: Dan Yasny <dyasny(a)redhat.com>
Datum: 2012.07.29 12:55
Kopia: users(a)ovirt.org
Ärende: Re: [Users] host raiding two LUN from different external
storage
You can use replicated at the SAN level storage between different
DCs, for DR. You can also use Gluster for the same purpose.
Setting RAID1 between two geographically separate hosts is asking for
trouble.
----- Original Message -----
> From: "Johan Kragsterman" <johan.kragsterman(a)capvert.se>
> To: users(a)ovirt.org
> Sent: Sunday, 29 July, 2012 12:08:20 PM
> Subject: [Users] host raiding two LUN from different external
> storage
>
> Hi!
>
> In some setups, like when you got two datacenters that works like
> failover sites, you would like to have two external raid
> controllers(storage devices), one in each datacenter.
>
> You then send two identical LUN's, from each controller, to a
> cluster, let's say two hosts, for simplicity. What you normally do
> is to host raid these LUN's in mirror(raid 1), so the hosts write
> the same to both LUN's, and both controllers.
>
> Question for me here is if I can accomplish this in oVirt
> management?
> Because if I can't, it will be a problem, because if I host raid at
> the host level, then the storage would be local storage for oVirt,
> wouldn't it? And then I suppose it can't be used for live
> migration,
> can it?
>
> Regrds Johan
> _______________________________________________
> Users mailing list
> Users(a)ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
>
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
1:20 a.m.
New subject: [Users] host raiding two LUN from different external storage.... continuation...
Hi again!
I continue, it was something I forgot to mention in last mail.
If the oVirt storage system could bring in two LUN's from different DC's, and use
LVM to join them as one mirrored unit, it would be exactly what I wanted. That would solve
a lot of issues.
But than of coarse the NPIV issue still remains...
Rgrds Johan
-----Dan Yasny <dyasny(a)redhat.com> skrev: -----
Till: Johan Kragsterman <johan.kragsterman(a)capvert.se>
Från: Dan Yasny <dyasny(a)redhat.com>
Datum: 2012.07.29 12:55
Kopia: users(a)ovirt.org
Ärende: Re: [Users] host raiding two LUN from different external storage
You can use replicated at the SAN level storage between different DCs, for DR. You can
also use Gluster for the same purpose.
Setting RAID1 between two geographically separate hosts is asking for trouble.
----- Original Message -----
From: "Johan Kragsterman"
<johan.kragsterman(a)capvert.se>
To: users(a)ovirt.org
Sent: Sunday, 29 July, 2012 12:08:20 PM
Subject: [Users] host raiding two LUN from different external storage
Hi!
In some setups, like when you got two datacenters that works like
failover sites, you would like to have two external raid
controllers(storage devices), one in each datacenter.
You then send two identical LUN's, from each controller, to a
cluster, let's say two hosts, for simplicity. What you normally do
is to host raid these LUN's in mirror(raid 1), so the hosts write
the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management?
Because if I can't, it will be a problem, because if I host raid at
the host level, then the storage would be local storage for oVirt,
wouldn't it? And then I suppose it can't be used for live migration,
can it?
Regrds Johan
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
--
Regards,
Dan Yasny
Red Hat Israel
+972 9769 2280
11:24 a.m.
IMHO, host level raid means software raid in one local node. In order
to support live migration, we should clone the
software raid in the destination node and make sure all the data are
flushed into the external storage device before
migration starts.
On 2012-7-29 17:08, Johan Kragsterman wrote:
Hi!
In some setups, like when you got two datacenters that works like failover sites, you
would like to have two external raid controllers(storage devices), one in each
datacenter.
You then send two identical LUN's, from each controller, to a cluster, let's say
two hosts, for simplicity. What you normally do is to host raid these LUN's in
mirror(raid 1), so the hosts write the same to both LUN's, and both controllers.
Question for me here is if I can accomplish this in oVirt management? Because if I
can't, it will be a problem, because if I host raid at the host level, then the
storage would be local storage for oVirt, wouldn't it? And then I suppose it can't
be used for live migration, can it?
Regrds Johan
_______________________________________________
Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
--
Shu Ming <shuming(a)linux.vnet.ibm.com>
IBM China Systems and Technology Laboratory
4526
days inactive
4530
days old
6 comments
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