Re: [gentoo-user] Strategy for using SAN/NAS for storage with Gentoo...

[Andrea Conti <alyf@alyf.net>]

> 1. Are there reliability issues surrounding this technology in Gentoo?

My only experience is with a Gentoo-based iSCSI target (ie. "server");
my clients are windows-based. The system is a low-end Core 2 duo running
the latest stable kernel and Iscsi Enterprise Target; I have been
running this setup non-stop for a couple of years and it has proven
quite stable.

iSCSI is designed with a dedicated, reliable network in mind, and in my
experience it is quite sensitive to network connectivity issues. It is
best used over gigabit ethernet; fast ethernet is ok, too, if you don't
care about performace. Avoid WiFi if you value your data (and your
mental health)

> 2. Are there any howtos about putting as much of the file-system as
> possible onto an iSCSI device.

Google "root over iscsi". For example:

http://wpkg.org/Diskless_/_remote_boot_with_Open-iSCSI

I have _not_ tried it. It is an interesting concept, but I think that
the OS is better left on a local disk -- the performance penalty is way
too great, especially with the king of budget-oriented storage backend
you are considering.

> 3. What's the best (most lightweight) way to expose the disk as a
> block device. I don't want to manage three fully-fledged Linux boxes.

The only software you need is an iSCSI initiator: a minimal Gentoo
install running sys-block/iscsitarget is enough.

IET allows you to export any kind of raw block device (a disk, a
partition, a RAID volume,...) or even a file on a local filesystem.

Or perhaps you can look into FreeNAS (http://freenas.org), which is less
flexible than a full-fledged OS install but might be enough in your case.

> Can (cheap) NAS devices be used to export iSCSI to Gentoo?

If the NAS device can "speak" iSCSI, well, yes.

> 4. What would be the strategy to 'secure' this iSCSI device... it would
> be a disaster if my WiFi were cracked and my data corrupted from a
> non-authorised host.

iSCSI connections are authenticated with a challenge-response mechanism;
in IET you can also restrict access to specific hosts on a per-volume
basis. That should be enough if you are not transferring the data itself
over WiFi, which is a Bad Thing and should not be done.

> Snap-shots, of course, are only really valuable for non-archive data...
> so, in future, I could add a ZFS volume using the same iSCSI strategy.

ZFS allows you to take FS-level snapshots -- with iSCSI that would be on
the client, onto a network-connected volume, and I don't know what kind
of performance implications that has.

If you want to take snapshots on the server, my first thought would be
to do so at the block level using LVM. No idea if it plays well with
IET, though.

andrea