[CentOS] iSCSI disk preperation

[Dr. Ed Morbius]

on 13:56 Mon 07 Feb, 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.

What are you using for your iSCSI target (storage array)?

Generally, RAID management of the storage is managed on the target side.
You'd use the target's native abilities to create/manage RAID arrays to
configure one or more physical disks as desired.  If you're using a
dedicated vendor product, it should offer these capabilities through
some interface or another.

Presentation of the iSCSI device is as a block storage device to the
initiator (host mounting the array).  That's going to be an
unpartitioned device.  You can either further partition this device or
use it as raw storage.  If you're partitioning it, and using multipath,
you'll have to muck with kpartx to make multipath aware of the
partitions.

We've elected to skip this locally and create a filesystem on the iSCSI
device directly.

Creating and mounting filesystems are both generally managed on the
initiator.

Truth is, there's a lot of flexibility with iSCSI, but not a lot of
guidance as to best practices that I could find.  Vendor docs have
tended to be very poor.  Above is my recommendation, and should
generally work.  Alternate configurations are almost certainly possible,
and may be preferable.

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