Kent Watsen wrote: >> What are you *most* interested in for this server? Reliability? >> Capacity? High Performance? Reading or writing? Large contiguous reads >> or small seeks? >> >> One thing that I did that got a good feedback from this list was >> picking apart the requirements of the most demanding workflow I >> imagined for the machine I was speccing out. > My first posting contained my use-cases, but I'd say that video > recording/serving will dominate the disk utilization - thats why I'm > pushing for 4 striped sets of RAIDZ2 - I think that it would be all > around goodness
It sounds good, that way, but (in theory), you'll see random I/O suffer a bit when using RAID-Z2: the extra parity will drag performance down a bit. The RAS guys will flinch at this, but have you considered 8*(2+1) RAID-Z1? I don't want to over-pimp my links, but I do think my blogged experiences with my server (also linked in another thread) might give you something to think about: http://lindsay.at/blog/archive/tag/zfs-performance/ > >> I'm learning more and more about this subject as I test the server >> (not all that dissimilar to what you've described, except with only 18 >> disks) I now have. I'm frustrated at the relative unavailability of >> PCIe SATA controller cards that are ZFS-friendly (i.e., JBOD), and the >> relative unavailability of motherboards that support both the latest >> CPUs as well as have a good PCI-X architecture. > Good point - another reply I just sent noted a PCI-X sata controller > card, but I'd prefer a PCIe card - do you have a recommendation on a > PCIe card? Nope, but I can endorse the Supermicro card you mentioned. That's one component in my server I have few doubts about. When I was kicking around possibilities on the list, I started out thinking about Areca's PCIe RAID drivers, used in JBOD mode. The on-list consensus was that they would be overkill. (Plus, there's the reliance on Solaris drivers from Areca.) It's true, for my configuration: disk I/O far exceeds the network I/O I'll be dealing with. Testing 16 disks locally, however, I do run into noticeable I/O bottlenecks, and I believe it's down to the top limits of the PCI-X bus. > As far as a mobo with "good PCI-X architecture" - check out > the latest from Tyan (http://tyan.com/product_board_detail.aspx?pid=523) > - it has three 133/100MHz PCI-X slots I use a Tyan in my server, and have looked at a lot of variations, but I hadn't noticed that one. It has some potential. Still, though, take a look at the block diagram on the datasheet: that actually looks like 1x PCI-X 133MHz slot and a bridge sharing 2x 100MHz slots. My benchmarks so far show that putting a controller on a 100MHz slot is measurably slower than 133MHz, but contention over a single bridge can be even worse. hth, adam _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
