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. Later, Tom _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list
