Xen users - Nov 2008 - Re: AW: Shared volume: Software-ISCSI or GFS or OCFS2?

I''m not sure where or how you want to use software iSCSI - maybe you
could provide a more thorough description of your Xen environment?

As far as OCFS vs GFS, you can use whichever you like.  I use OCFS2 for two
reasons: first because it''s included with SLES 10, and second because I
find it slightly easier to configure than GFS.  It has its downsides, too,
though, but works fine for me.  Use whichever cluster-aware FS you want.

-Nick
Nick Couchman
Manager, Information Technology 
-----Original Message-----
From: "Rustedt, Florian" <Florian.Rustedt@smartnet.de>
To: Nick Couchman <Nick.Couchman@seakr.com>

Sent: 11/17/2008 2:09:13 AM
Subject: AW: [Xen-users] Shared volume: Software-ISCSI or GFS or OCFS2?

Ok?
So what''s the real advantage of using "software-iscsi" then
for me?
And what about GFS instead of OCFS2?
 
Kind regards, Florian

________________________________

Von: Nick Couchman [mailto:Nick.Couchman@seakr.com] 
Gesendet: Freitag, 14. November 2008 17:23
An: Rustedt, Florian
Cc: xen-users@lists.xensource.com
Betreff: Re: [Xen-users] Shared volume: Software-ISCSI or GFS or OCFS2?


Well, I''m not sure it''s a matter of iSCSI OR a filesystem, but
that
depends on how you decide to go about setting it up.  In my environment,
I have both iSCSI and FC access to the same volumes.  Some of my servers
have FC HBAs and connect to my XEN volume that way, some of them have
hardware iSCSI HBAs, and some of them use software iSCSI initiators.  I
have three XEN volumes - one for server domUs, one for VDI domUs, and
one for development domUs.  All of these volumes are formatted with
OCFS2 so that I can mount them on all of my servers.  The domUs then use
file-based disks that reside on the shared volumes, so I can migrate
them back and forth between servers relatively easily.

You could use iSCSI to do individual volumes for each of your domUs - I
found it a bit cumbersome to have to go into either EVMS or LVM each
time I wanted to create a domU and create a volume for it, so I''m
sticking with the file-based approach.

-Nick


-----Original Message-----
From: Rustedt, Florian <Florian.Rustedt@smartnet.de
<mailto:%22Rustedt,%20Florian%22%20%3cFlorian.Rustedt@smartnet.de%3e> >
To: xen-users@lists.xensource.com
Subject: [Xen-users] Shared volume: Software-ISCSI or GFS or OCFS2?
Date: Fri, 14 Nov 2008 11:09:33 +0100


Hello list,

I want to use shared volumes between severall vm''s and defenetly
don''t
want to use NFS or Samba!

So i have three options:
1. simulated(software-) iscsi
2. GFS
3. OCFS2

What do you suggest and why?

Kind regards, Florian
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I am "swimming around" for choosing the right technology to implement
shared partititions between several vms'' like /usr, /lib and
/lib/modules, etc.

For that, i need to mount them mostly RO, but on one host RW, so that this host
is the one where i can install/delete software and that''s applied to
all readonly-connects.

I tried that with an normal xfs-partition and it crashes if i mount it in
different modes: the ro-clients got IO-errors.

So i decided to find out more ways and first tried lvm-snapshots mounted rw, but
they crashed, too.

So far now, i am at the point that i think that the best way is to use a
cluster-aware file-system on the partitions?

First i thought, iscsi has some kind of integrated data-locking-mechanism so i
can mount it multiple times without errors, but in between i know, that this is
done by the filesystem, so iscsi seems to be no more interesting any more..

So best advice would be to format my shared partitions with GFS or OCFS2 and use
them shared?

Kind regards, Florian

-----Ursprüngliche Nachricht-----
Von: Nick Couchman [mailto:Nick.Couchman@seakr.com] 
Gesendet: Montag, 17. November 2008 15:53
An: Rustedt, Florian
Cc: xen-users@lists.xensource.com
Betreff: Re: AW: [Xen-users] Shared volume: Software-ISCSI or GFS orOCFS2?

I''m not sure where or how you want to use software iSCSI - maybe you
could provide a more thorough description of your Xen environment?

As far as OCFS vs GFS, you can use whichever you like.  I use OCFS2 for two
reasons: first because it''s included with SLES 10, and second because I
find it slightly easier to configure than GFS.  It has its downsides, too,
though, but works fine for me.  Use whichever cluster-aware FS you want.

-Nick
Nick Couchman
Manager, Information Technology
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> So far now, i am at the point that i think that the best way is to use a
> cluster-aware file-system on the partitions?
Why not NFS?  Cluster filesystems sound like overkill for this scenario.

John



-- 
John Madden
Sr. UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden@ivytech.edu

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...well, because i had too much trouble with NFS in the last 10 years under
linux.
I don''t like it at all because of stability and deadlocks and so on...

No prob for me to learn something new with cluster-aware filesystems, though ;)

Kind regards, Florian

-----Ursprüngliche Nachricht-----
Von: John Madden [mailto:jmadden@ivytech.edu] 
Gesendet: Montag, 17. November 2008 16:59
An: xen-users@lists.xensource.com
Cc: Rustedt, Florian; Nick Couchman
Betreff: Re: AW: AW: [Xen-users] Shared volume: Software-ISCSI or GFS orOCFS2?
> So far now, i am at the point that i think that the best way is to use 
> a cluster-aware file-system on the partitions?
Why not NFS?  Cluster filesystems sound like overkill for this scenario.

John



--
John Madden
Sr. UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden@ivytech.edu
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On Monday 17 November 2008 11:10:03 am Rustedt, Florian
wrote:
>  ...well, because i had too much trouble with NFS in the last 10 years
> under linux. I don''t like it at all because of stability and
deadlocks and
> so on...
Particularly if you''re talking read-only, you really shouldn''t
be having
problems like this.  I''ve served 50-million-file filesystems over NFS
to
clusters serving 20-million-pages/day.  NFS will work fine.
> No prob for me to learn something new with cluster-aware filesystems,
> though ;)
And have 10 years worth of new troubles... ;)

John




-- 
John Madden
Sr. UNIX Systems Engineer
Ivy Tech Community College of Indiana
jmadden@ivytech.edu

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