Xen users - Nov 2010 - Opinion on best way to use network storage

I need the community''s opinion on the best way to use my storage SAN to
host
xen images.  The SAN itself is running iSCSI and NFS.  My goal is to keep
all my xen images on the SAN device, and to be able to easily move images
from one host to another as needed while minimizing storage requirements and
maximizing performance.

What I see are my options:

1) Export a directory through NFS.  Create image files on the NFS mount and
have each zen guest use the image off the NFS mount.  This has the benefit
of all images being visible to all hosts (on the NFS mount), but I''m
not
sure about the performance.
2) Create an image on the SAN server for each XEN host and export it to the
XEN servers through iSCSI.  The XEN server will see it as a VolumeGroup.
 Create Logical Volumes in the VolumeGroup for each XEN guest.  Has the
advantage of using LVM for the guest instead of an image file (which is
rumored to be faster).  Disadvantage is individual images are not easily
moved to other hosts
3) Create a image on the SAN server for each XEN guest and export it through
iSCSI.  Attach XEN guests directly to the iSCSI image.  Has the advantage of
being portable to other hosts, maybe more efficient?

Thanks in advance


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On Friday 12 November 2010 04:28:46 VPS Lime wrote:
> I need the community''s opinion on the best way to use my storage
SAN to
> host xen images.  The SAN itself is running iSCSI and NFS.  My goal is to
> keep all my xen images on the SAN device, and to be able to easily move
> images from one host to another as needed while minimizing storage
> requirements and maximizing performance.
> 
> What I see are my options:
> 
> 1) Export a directory through NFS.  Create image files on the NFS mount and
> have each zen guest use the image off the NFS mount.  This has the benefit
> of all images being visible to all hosts (on the NFS mount), but
I''m not
> sure about the performance.
> 2) Create an image on the SAN server for each XEN host and export it to the
> XEN servers through iSCSI.  The XEN server will see it as a VolumeGroup.
>  Create Logical Volumes in the VolumeGroup for each XEN guest.  Has the
> advantage of using LVM for the guest instead of an image file (which is
> rumored to be faster).  Disadvantage is individual images are not easily
> moved to other hosts
> 3) Create a image on the SAN server for each XEN guest and export it
> through iSCSI.  Attach XEN guests directly to the iSCSI image.  Has the
> advantage of being portable to other hosts, maybe more efficient?
> 
> Thanks in advance
Do you want to snapshot your Xen guest storage by means of LVM?

B.

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I''m using OCFS2, another possibility is CLVM or
GFS(requires hardware fencing support).



On Fri, Nov 12, 2010 at 7:11 AM, Bart Coninckx
<bart.coninckx@telenet.be>wrote:
> On Friday 12 November 2010 04:28:46 VPS Lime wrote:
> > I need the community''s opinion on the best way to use my
storage SAN to
> > host xen images.  The SAN itself is running iSCSI and NFS.  My goal is
to
> > keep all my xen images on the SAN device, and to be able to easily
move
> > images from one host to another as needed while minimizing storage
> > requirements and maximizing performance.
> >
> > What I see are my options:
> >
> > 1) Export a directory through NFS.  Create image files on the NFS
mount
> and
> > have each zen guest use the image off the NFS mount.  This has the
> benefit
> > of all images being visible to all hosts (on the NFS mount), but
I''m not
> > sure about the performance.
> > 2) Create an image on the SAN server for each XEN host and export it
to
> the
> > XEN servers through iSCSI.  The XEN server will see it as a
VolumeGroup.
> >  Create Logical Volumes in the VolumeGroup for each XEN guest.  Has
the
> > advantage of using LVM for the guest instead of an image file (which
is
> > rumored to be faster).  Disadvantage is individual images are not
easily
> > moved to other hosts
> > 3) Create a image on the SAN server for each XEN guest and export it
> > through iSCSI.  Attach XEN guests directly to the iSCSI image.  Has
the
> > advantage of being portable to other hosts, maybe more efficient?
> >
> > Thanks in advance
>
> Do you want to snapshot your Xen guest storage by means of LVM?
>
> B.
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>

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On Friday 12 November 2010 14:29:48 Jorge Viana wrote:
> I''m using OCFS2, another possibility is CLVM or
> GFS(requires hardware fencing support).
> 
> On Fri, Nov 12, 2010 at 7:11 AM, Bart Coninckx 
<bart.coninckx@telenet.be>wrote:
> > On Friday 12 November 2010 04:28:46 VPS Lime wrote:
> > > I need the community''s opinion on the best way to use my
storage SAN to
> > > host xen images.  The SAN itself is running iSCSI and NFS.  My
goal is
> > > to keep all my xen images on the SAN device, and to be able to
easily
> > > move images from one host to another as needed while minimizing
> > > storage requirements and maximizing performance.
> > > 
> > > What I see are my options:
> > > 
> > > 1) Export a directory through NFS.  Create image files on the NFS
mount
> > 
> > and
> > 
> > > have each zen guest use the image off the NFS mount.  This has
the
> > 
> > benefit
> > 
> > > of all images being visible to all hosts (on the NFS mount), but
I''m
> > > not sure about the performance.
> > > 2) Create an image on the SAN server for each XEN host and export
it to
> > 
> > the
> > 
> > > XEN servers through iSCSI.  The XEN server will see it as a
> > > VolumeGroup.
> > > 
> > >  Create Logical Volumes in the VolumeGroup for each XEN guest. 
Has the
> > > 
> > > advantage of using LVM for the guest instead of an image file
(which is
> > > rumored to be faster).  Disadvantage is individual images are not
> > > easily moved to other hosts
> > > 3) Create a image on the SAN server for each XEN guest and export
it
> > > through iSCSI.  Attach XEN guests directly to the iSCSI image. 
Has the
> > > advantage of being portable to other hosts, maybe more efficient?
> > > 
> > > Thanks in advance
> > 
> > Do you want to snapshot your Xen guest storage by means of LVM?
> > 
> > B.
> > 
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@lists.xensource.com
> > http://lists.xensource.com/xen-users
It was my understanding CLVM does not support snapshotting. Too bad, a CoW 
solution would be ideal for you.


B.

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We''ve done 3) by creating a LUN on the SAN for each domU.  Works well,
and is nice to use on a SAN that has snapshot support.  Rather than
running iscsi (or aoe) in the guest, we open all LUNs on the dom0 and
export each to its respective domU via xenblk.

 

On a SAN with a limited number of LUNs, we also did 2) but with CLVM on
the dom0 hosts.  That allowed each dom0 in the cluster to view each
logical volume.  Migrations are easy but as noted elsewhere, CLVM has no
snapshot support.  Has the advantage that logical volume labels are nice
and descriptive.

 

Disk performance either way is limited by the SAN and network, and can
be quite good.  I''ve successfully virtualized database servers and
other
hosts with intensive I/O requirements.

 

-Jeff

 

From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of VPS Lime
Sent: Thursday, November 11, 2010 10:29 PM
To: xen-users@lists.xensource.com
Subject: [Xen-users] Opinion on best way to use network storage

 

I need the community''s opinion on the best way to use my storage SAN to
host xen images.  The SAN itself is running iSCSI and NFS.  My goal is
to keep all my xen images on the SAN device, and to be able to easily
move images from one host to another as needed while minimizing storage
requirements and maximizing performance. 

 

What I see are my options:

 

1) Export a directory through NFS.  Create image files on the NFS mount
and have each zen guest use the image off the NFS mount.  This has the
benefit of all images being visible to all hosts (on the NFS mount), but
I''m not sure about the performance.

2) Create an image on the SAN server for each XEN host and export it to
the XEN servers through iSCSI.  The XEN server will see it as a
VolumeGroup.  Create Logical Volumes in the VolumeGroup for each XEN
guest.  Has the advantage of using LVM for the guest instead of an image
file (which is rumored to be faster).  Disadvantage is individual images
are not easily moved to other hosts

3) Create a image on the SAN server for each XEN guest and export it
through iSCSI.  Attach XEN guests directly to the iSCSI image.  Has the
advantage of being portable to other hosts, maybe more efficient?  

 

Thanks in advance

 

 



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