Only because I was asked. :)
Dean Hamstead wrote:
this is flame bait : i cant think of anything that is specific to redhat and its friends. perhaps there are some strange SAN drivers which only work on redhat. if that is the case, you need to ask yourself what sort of life is this hardware likely to have? if i update the kernel will it make the hardware useless? binary drivers and software suffer from bit-rot horribly in linux.
No, it's not flame bait, it's just ill-informed (so I stand by my comments earlier on that line). Nearly all SAN systems have fibre-SCSI attachment -- this goes for all of the major SAN vendors -- EMC, Hitachi, Fujitsu, etc. To make the SAN switch work in failover mode, you need specific hardware -- usually EMC/Lightpulse style or QLogic chipset (there are third party OEM boards using these chipsets) dual-fibre SCSI cards. The business of automatic-failover and detection of reconnects on these systems is still pretty much a black art, and all of the drivers to do it are closed source. The majority of them are only available for Red Hat in the Linux universe, while the rest are available for either Red Hat or SuSE. No other distro choices, sorry. There are the beginnings of an open-source driver in the kernel (provided by Red Hat in fact) but it just doesn't have the features of the closed-source drivers. e.g. multipath works but failover does not. So the closed source drivers are available (at a cost) for every version of RHEL and most recent versions of SuSE, and they are tied to a specific kernel version and they don't suffer from bit-rot because there are large companies being paid significant amounts of money to keep them updated. I doubt that every major SAN hardware vendor is going to go out of business because their drivers aren't available on Debian, or aren't available to people who roll their own kernels. No, you get RHEL, you install that, the drivers are available for that version of RHEL (RHEL never updates its kernel, only backports patches, so the drivers remain good over time), and you use that. No Debian, no gentoo, no Ubuntu, and no Fedora Core. And you aren't going to get major data centers pulling out their SAN storage units and stringing together heaps of USB drives or something just so they can run without the binary drivers. There are hundreds of millions of dollars invested in this stuff, it's good, it's stable, and it works. You want to connect 1000 servers up to 500TB of disk storage, have it work reliably, and have cluster file systems so you can have large oracle / OCFS / GFS clusters, with SCSI path redundancy and load balancing? This is the way it's done, end of story. -- Del -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
