Re: [zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
richard.ell...@richardelling.com said: We are starting to see a number of SAS HDDs that prefer logical-block to round-robin. I see this with late model Seagate and Toshiba HDDs. There is another, similar issue with recognition of multipathing by the scsi_vhci driver. Both of these are being tracked as https://www.illumos.org/ issues/644 and there is an alternate scsi_vhci.conf file posted in that bugid. Interesting, I just last week had a Toshiba come from Dell as a replacement for a Seagate 2TB SAS drive; On Solaris-10, the Toshiba insisted on showing up as 2 drives, so mpxio was not recognizing it. Fortunately I was able to swap the drive for a Seagate, but I'll stash away a copy of the scsi_vhci.conf entry for the future. We're considering making logical-block the default (as in above bugid) and we have not discovered a reason to keep round-robin. If you know of any reason why round-robin is useful, please add to the bugid. Should be fine. When I first ran into this a couple years ago, I did a lot of tests and found logical-block to be slower than none (with those Seagate 2TB SAS drives in Dell MD1200's), but not a whole lot slower. I vaguely recall that round-robin was better for highly random, small I/O (IOPS-intensive) workloads. I got the best results by manually load-balancing half the drives to one path and half the drives to the other path. But I decided it was not worth the effort. Maybe if there was a way to automatically do that (with a relatively static result) Of course, this was all tested on Solaris-10, so your mileage may vary. Regards, Marion ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
Are these issues something to watch out for on Solaris 11 as well? Thx in advance… -Anh On Apr 9, 2012, at 12:43 PM, Marion Hakanson wrote: richard.ell...@richardelling.com said: We are starting to see a number of SAS HDDs that prefer logical-block to round-robin. I see this with late model Seagate and Toshiba HDDs. There is another, similar issue with recognition of multipathing by the scsi_vhci driver. Both of these are being tracked as https://www.illumos.org/ issues/644 and there is an alternate scsi_vhci.conf file posted in that bugid. Interesting, I just last week had a Toshiba come from Dell as a replacement for a Seagate 2TB SAS drive; On Solaris-10, the Toshiba insisted on showing up as 2 drives, so mpxio was not recognizing it. Fortunately I was able to swap the drive for a Seagate, but I'll stash away a copy of the scsi_vhci.conf entry for the future. We're considering making logical-block the default (as in above bugid) and we have not discovered a reason to keep round-robin. If you know of any reason why round-robin is useful, please add to the bugid. Should be fine. When I first ran into this a couple years ago, I did a lot of tests and found logical-block to be slower than none (with those Seagate 2TB SAS drives in Dell MD1200's), but not a whole lot slower. I vaguely recall that round-robin was better for highly random, small I/O (IOPS-intensive) workloads. I got the best results by manually load-balancing half the drives to one path and half the drives to the other path. But I decided it was not worth the effort. Maybe if there was a way to automatically do that (with a relatively static result) Of course, this was all tested on Solaris-10, so your mileage may vary. Regards, Marion ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
On Apr 6, 2012, at 4:58 PM, Marion Hakanson wrote: a...@blackandcode.com said: I'm spec'ing out a Thumper-esque solution and having trouble finding my favorite Hitachi Ultrastar 2TB drives at a reasonable post-flood price. The Seagate Constellations seem pretty reasonable given the market circumstances but I don't have any experience with them. Anybody using these in their ZFS systems and have you had good luck? We have a lot of 2TB and 3TB Seagates here, they work fine. Most of ours are the Nearline-SAS variety, in Dell MD1200 enclosures, used on Windows Linux behind PERC H800 RAID cards, and on Solaris-10 and OpenIndiana behind LSI SAS HBA's. We do have one new server with a pile of 2TB SATA Seagate's as well, so far working fine. The only caveat I've found is that the Nearline SAS Seagates go really slow with the Solaris default multipath load-balancing setting (round-robin). Set it to none or some large block value and they go fast. This issue doesn't appear when used with the PERC H800's. We are starting to see a number of SAS HDDs that prefer logical-block to round-robin. I see this with late model Seagate and Toshiba HDDs. There is another, similar issue with recognition of multipathing by the scsi_vhci driver. Both of these are being tracked as https://www.illumos.org/issues/644 and there is an alternate scsi_vhci.conf file posted in that bugid. We're considering making logical-block the default (as in above bugid) and we have not discovered a reason to keep round-robin. If you know of any reason why round-robin is useful, please add to the bugid. -- richard -- ZFS Performance and Training richard.ell...@richardelling.com +1-760-896-4422 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
Happy Friday, List! I'm spec'ing out a Thumper-esque solution and having trouble finding my favorite Hitachi Ultrastar 2TB drives at a reasonable post-flood price. The Seagate Constellations seem pretty reasonable given the market circumstances but I don't have any experience with them. Anybody using these in their ZFS systems and have you had good luck? Also, if anyone has a line on a used/refurbished/reconditioned X4540 (Thor), I'd love to hear from you. Thanks in advance!___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
On Fri, 6 Apr 2012, Marion Hakanson wrote: The only caveat I've found is that the Nearline SAS Seagates go really slow with the Solaris default multipath load-balancing setting (round-robin). Set it to none or some large block value and they go fast. This issue doesn't appear when used with the PERC H800's. If the drives are exposed as individual LUNs, then it may be possible to arrange things so that 1/2 the drives are accessed (by default) down one path, and the other 1/2 down the other. That way you get the effect of load-balancing without the churn which might be caused by dynamic load-balancing. That is what I did for my storage here, but the preferences needed to be configured on the remote end. It is likely possible to configure everything on the host end but Solaris has special support for my drive array so it used the drive array's preferences. Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer,http://www.GraphicsMagick.org/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Seagate Constellation vs. Hitachi Ultrastar
I've seen a couple sources that suggest prices should be dropping by the end of April -- apparently not as low as pre flood prices due in part to a rise in manufacturing costs but about 10% lower than they're priced today. -Gary ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
