[CentOS] iSCSI disk preperation

Tue Feb 8 00:58:55 UTC 2011
Dr. Ed Morbius <dredmorbius at gmail.com>

on 15:26 Mon 07 Feb, Ross Walker (rswwalker at gmail.com) wrote:
> On Mon, Feb 7, 2011 at 1:56 PM, Jason Brown
> <jason.brown at millbrookprinting.com> wrote:
> > I am currently going through the process of installing/configuring an
> > iSCSI target and cannot find a good write up on how to prepare the disks
> > on the server.  I would like to mirror the two disks and present them to
> > the client.  Mirroring isn't the question, its how I go about it is the
> > problem.  When I partitioned the two drives and mirrored them together,
> > then presented them to the client, it showed to the client as a disk out
> > no partion on it.  Should I partition the drive again and then lay the
> > file system down on top of that?  Or should I delete the partitions on
> > the target server and just have sda and sdb mirrored, then when the
> > client attaches the disk, then partion it (/dev/sdc1) and write the file
> > system.
> 
> Whatever you export, the whole disk, partition or logical volume, the
> initiator will see as a whole disk.
> 
> So if you mirror sdaX and sdbX and export md0 the initiator will see a
> disk the size and contents of sdaX/sdbX.
> 
> Just create the filesystem on the disk on the initiator and use it there.
> 
> REMEMBER: iSCSI isn't a way for multiple initiators to share the same
> disk (though they can using specialized clustering file systems), it
> is a way for multiple initiators to share the same disk subsystem.

*OR* as a special case, if access is *only* read-only (or read-only to
all but one initiator).
 
> You can't access the file system from both the target-side and
> initiator-side at once or it will corrupt the file system. If that's
> what you want then you want NFS or Samba and not iSCSI.

Right, or other network-aware filesystem (andrew, coda, gluster), none
of which are particularly widely used.

  http://en.wikipedia.org/wiki/List_of_file_systems#Distributed_file_systems


-- 
Dr. Ed Morbius
Chief Scientist                                   When you need power
Krell Power Systems Unlimited                        Go to Krell!