iSCSI boot enablement != iSCSI HBA. All that will do is allow your NIC
to mount an iSCSI device as a boot drive and load the first few blocks
from it (i.e. a bootloader). When the kernel actually loads into memory
and boots, it will need to be able to do the following before it can
actually load the OS past the initrd:
1. Start up the NIC
2. Run DHCP (or set a static IP)
3. Load the iSCSI daemon
4. Initiate a connection to the iSCSI shelf which should create
/dev/<something> (I think...been a while since I did iSCSI)
5. Mount the iSCSI LUN (/dev/something) as root.
Whereas in the situation with an iSCSI HBA (as we've all been
recommending) the kernel only needs to do the following:
1. Load the driver for the iSCSI HBA which creates /dev/<whatever>
2. Mount root on /dev/<whatever>
Obviously the second method is much better supported since it's exactly
the same as booting from a locally-attached disk or a FC SAN or something.
Paul Krizak 7171 Southwest Pkwy MS B400.2B
Senior Systems Engineer Austin, TX 78735
Advanced Micro Devices Desk: (512) 602-8775
Linux/Unix Systems Engineering Cell: (512) 791-0686
Silicon Design Division Fax: (512) 602-0468
Ugo Bellavance wrote:
Tom Sightler a écrit :
On Thu, 2009-07-16 at 14:55 -0400, Ugo Bellavance wrote:
Hi,
I have blade servers that I'd like to boot directly on an iSCSI
drive. Is it possible on RHEL5? Will it be possible in RHEL6?
I saw this: http://iscsi-init.sourceforge.net/HOWTO.html. Would that
be a solution?
I'd suggest an iSCSI HBA if you want to go this route. We boot quite a
number of systems via iSCSI with Qlogic iSCSI HBA's, including several
RHEL4 and RHEL5 systems (well, actually only a couple of RHEL4 systems
left). My experiences with software iSCSI boot were far less
successful. Just took too many hacks and broke too many ways. I'll
admit we haven't tried in almost two years, so support may have
improved.
I just realized I had HP NC532i multifunction NICs in those blades, and
they're iSCSI-boot enabled. I'll work on that, but that looks promising.
Ugo
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