Tom Sightler a écrit :
On Fri, 2009-07-17 at 10:03 -0400, Ugo Bellavance wrote:
Paul Krizak a écrit :
I whole-heartedly agree with this post. I've had the same experiences,
not more than 6 months ago, with RHEL5.2 as the platform. A hardare
iSCSI HBA is definitely the way to go if you need to use iSCSI for
primary storage.
I didn't even know that existed.
Does this http://h30094.www3.hp.com/product.asp?sku=3867559&pagemode=ca
looks like it?
I can't really explain myself what is the difference between that and a
regular NIC, though...
It's really pretty simple, an iSCSI HBA has all of the support for iSCSI
built into the BIOS of the card. It pretty much does the same thing for
iSCSI that a Fiber Channel HBA does, provide all the support discovering
targets on the iSCSI network and presenting them to the host as SCSI
devices directly within the card firmware.
A NIC is just a NIC, it doesn't have any special knowledge any specific
protocol so all the support for iSCSI has to come from the system BIOS
or the operating system itself. The NIC may have iSCSI TOE (TCP
Offload) which improves iSCSI performance when used with proper drivers,
but it still needs host or OS support to actually recognize and preset
iSCSI devices.
I don't want to imply that software iSCSI isn't usable, we use software
iSCSI quite a bit on servers that already boot from local disk, however,
we've found that boot-from-iSCSI environments are simply easier with
iSCSI HBA's and actually, we include iSCSI HBA's on any host that uses
iSCSI as it's primary storage, just as Paul suggested. Our experience
has been that this works best. We're a nearly 100% iSCSI shop and have
been for several years (mostly Dell Equallogic, with a single EMC
AX150i, and a sprinkling of cheap third-party iSCSI arrays for second
tier storage) so we have a lot of experience in this space and the
Qlogic iSCSI HBA's have been workhorses for us in all of our
environments, VMware, Windows, and RHEL, thus it's hard for me to
suggest anything else.
So you mean that you're using boot-on-scsi with Qlogic iSCSI HBS with
good results, even reliability-wise?
Thanks,
Ugo
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