On Wed, 5 Dec 2007, Brian Hechinger wrote: > I will be putting 4 500GB SATA disks in my Ultra80. I currently have > two 10K rpm 73G SCSI disks in it with 10G for the OS (UFS) and the > remaining space for a ZFS pool (the two remaining partitions are setup > in a mirror). > > Would it be worth my while to move all the data off of the zfs partitions > of the 73G disks and use those partitions for ZIL? Would I really gain > any performance from that?
Hi Brian, I don't think you'll see any worthwhile improvement. For a ZIL device, you really need something like a (small) SAS 15k RPM 3.5" drive - which will sustain 700 to 900 IOPS (my number - open to argument) - or a RAM disk or one of these [1]. 10K RPM SCSI disks will get (best case) 350 to 400 IOPS. Remember, the main issue with legacy SCSI is that (SCSI) commands are sent 8-bits wide at 5Mbits/Sec - for backwards compatibility. You simply can't send enough commands over a SCSI bus to busy out a modern 10k RPM SCSI drive. BTW, this is easy to verify: just buy the same drive, one with a SCSI interface and one with a SAS (or FC) interface, and in about 5 minutes, you'll be looking for a victim ^H^H^H^H^H^H buyer for the SCSI drive. PS: LsiLogic just updated their SAS HBAs and have a couple of products very reasonably priced IMHO. Combine that with a (single ?) Fujitsu MAX3xxxRC (where xxx represents the size) and you'll be wearing a big smile every time you work on a system so equipped. Tell Santa that you want an LsiLogic SAS HBA and some SAS disks for Xmas! :) [1] Finally, someone built a flash SSD that rocks (and they know how fast it is judging by the pricetag): http://www.tomshardware.com/2007/11/21/mtron_ssd_32_gb/ http://www.anandtech.com/storage/showdoc.aspx?i=3167 Regards, Al Hopper Logical Approach Inc, Plano, TX. [EMAIL PROTECTED] Voice: 972.379.2133 Fax: 972.379.2134 Timezone: US CDT OpenSolaris Governing Board (OGB) Member - Apr 2005 to Mar 2007 http://www.opensolaris.org/os/community/ogb/ogb_2005-2007/ Graduate from "sugar-coating school"? Sorry - I never attended! :) _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
