My system is currently using LSI 9211 HBAs with Crucial M4 SSDs for ZIL/L2ARC. I have used LSIUTIL v1.63 to disable the write cache on the two controllers with only SATA HDDs, though my third controller has a combination of HDD and SSD as shown:
SAS2008's links are down, down, 6.0 G, 6.0 G, 3.0 G, down, 3.0 G, 3.0 G > > B___T___L Type Vendor Product Rev PhyNum > 0 9 0 Disk ATA M4-CT064M4SSD2 0309 2 > 0 10 0 Disk ATA M4-CT064M4SSD2 0309 3 > 0 11 0 Disk ATA ST3500320NS SN06 4 > 0 12 0 Disk ATA ST3500320NS SN06 6 > 0 13 0 Disk ATA ST3500320NS SN06 7 > Unfortunately, the SATA write cache can only be turned on or off at the controller level with LSIUTIL. In a case where the SSD ZIL and L2ARC are on the same controller as pool HDDs, is it still recommended that the cache be disabled? My other thought is that the cache to which LSIUTIL is referring is located on the controller and that the write cache on the individual disks is still active. This excerpt shows the interactive prompts of LSIUTIL during and after disabling the cache: Main menu, select an option: [1-99 or e/p/w or 0 to quit] 14 > > Multi-pathing: [0=Disabled, 1=Enabled, default is 0] > SATA Native Command Queuing: [0=Disabled, 1=Enabled, default is 1] > SATA Write Caching: [0=Disabled, 1=Enabled, default is 1] 0 > > Main menu, select an option: [1-99 or e/p/w or 0 to quit] 68 > > Current Port State > ------------------ > SAS2008's links are down, down, 6.0 G, 6.0 G, 3.0 G, down, 3.0 G, 3.0 G > > Software Version Information > ---------------------------- > Current active firmware version is 0b000000 (11.00.00) > Firmware image's version is MPTFW-11.00.00.00-IT > LSI Logic > Not Packaged Yet > x86 BIOS image's version is MPT2BIOS-7.21.00.00 (2011.08.11) > > Firmware Settings > ----------------- > SAS WWID: <stripped> > Multi-pathing: Disabled > SATA Native Command Queuing: Enabled > SATA Write Caching: Disabled > SATA Maximum Queue Depth: 32 > SAS Max Queue Depth, Narrow: 0 > SAS Max Queue Depth, Wide: 0 > Device Missing Report Delay: 0 seconds > Device Missing I/O Delay: 0 seconds > Phy Parameters for Phynum: 0 1 2 3 4 5 6 7 > Link Enabled: Yes Yes Yes Yes Yes Yes Yes Yes > Link Min Rate: 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 > Link Max Rate: 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 > SSP Initiator Enabled: Yes Yes Yes Yes Yes Yes Yes Yes > SSP Target Enabled: No No No No No No No No > Port Configuration: Auto Auto Auto Auto Auto Auto Auto Auto > Interrupt Coalescing: Enabled, timeout is 10 us, depth is 4 > > Thank you! On Tue, Mar 13, 2012 at 7:58 AM, Edward Ned Harvey < opensolarisisdeadlongliveopensola...@nedharvey.com> wrote: > > From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > > boun...@opensolaris.org] On Behalf Of Cooper Hubbell > > > > Regarding the writeback cache on disks, what is the recommended method > > to disable the cache? Through HBA firmware, or via Solaris? > > It's the same either way - You press Ctrl-R (or whatever) during bootup > and disable the writeback in the perc BIOS... Or you use MegaCLI, which > does the same thing from within the OS. > > But again, I would only recommend disabling the writeback if you have > either a dedicated SSD log device (or equivalent or faster), ... Or if you > disable the ZIL completely (sync=disabled property). Because if you > actually have ZIL and use spindle disks for ZIL, then the writeback cache > is a big improvement over nothing. > >
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