Hmmn, that *sounds* as if you are saying you've a very-high-redundancy RAID1 mirror, 4 disks deep, on an 'enterprise-class tier 2 storage' array that doesn't support RAID 1+0 or 0+1.
That sounds weird: the 2540 supports RAID levels 0, 1, (1+0), 3 and 5, and deep mirrors are normally only used on really fast equipment in mission-critical tier 1 storage... Are you sure you don't mean you have raid 0 (stripes) 4 disks wide, each stripe presented as a LUN? If you really have 4-deep RAID 1, you have a configuration that will perform somewhat slower than any single disk, as the array launches 4 writes to 4 drives in parallel, and returns success when they all complete. If you had 4-wide RAID 0, with mirroring done at the host, you would have a configuration that would (probabilistically) perform better than a single drive when writing to each side of the mirror, and the write would return success when the slowest side of the mirror completed. --dave (puzzled!) c-b Tharindu Rukshan Bamunuarachchi wrote: > We do not use raidz*. Virtually, no raid or stripe through OS. > > We have 4 disk RAID1 volumes. RAID1 was created from CAM on 2540. > > 2540 does not have RAID 1+0 or 0+1. > > cheers > tharindu > > Brandon High wrote: > >>On Tue, Jul 22, 2008 at 10:35 PM, Tharindu Rukshan Bamunuarachchi >><[EMAIL PROTECTED]> wrote: >> >> >>>Dear Mark/All, >>> >>>Our trading system is writing to local and/or array volume at 10k >>>messages per second. >>>Each message is about 700bytes in size. >>> >>>Before ZFS, we used UFS. >>>Even with UFS, there was evey 5 second peak due to fsflush invocation. >>> >>>However each peak is about ~5ms. >>>Our application can not recover from such higher latency. >>> >>> >> >>Is the pool using raidz, raidz2, or mirroring? How many drives are you using? >> >>-B >> >> >> > > ------------------------------------------------------------------------ > > ******************************************************************************************************************************************************************* > > "The information contained in this email including in any attachment is > confidential and is meant to be read only by the person to whom it is > addressed. If you are not the intended recipient(s), you are prohibited from > printing, forwarding, saving or copying this email. If you have received this > e-mail in error, please immediately notify the sender and delete this e-mail > and its attachments from your computer." > > ******************************************************************************************************************************************************************* > > > ------------------------------------------------------------------------ > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- David Collier-Brown | Always do right. This will gratify Sun Microsystems, Toronto | some people and astonish the rest [EMAIL PROTECTED] | -- Mark Twain (905) 943-1983, cell: (647) 833-9377, (800) 555-9786 x56583 bridge: (877) 385-4099 code: 506 9191# _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
