Hi Bob; In all 2500 and 6000 series you can assign raid set's to a controller and that controller becomes the owner of the set. Generaly not force drives switching between controllers always one controller owns a disk, and other waits in standby. Some disks use ALUA and re-route traffic coming to the "not preferred" controller to preferred controller. While some companies market this a "true" active active set up, this reduces the performance significantly if the host is not %100 ALUA aware. While this architacture solves the problem of setting up MPXIO on hosts.
It's likely that sometime in future Sun may release a FW to enable ALUA on controllers but this definetly wont improve performance. The advantage of 2540 against it's bigger brothers (6140 which is EOL'ed) and competitors 2540 do use dedicated data paths for cache mirroring just like higher end unit disks (6180,6580, 6780) improving write performance significantly. Spliting load between controllers can most of the time increase performance, but you do not need to split in two equal partitions. Also do not forget that first tray have dedicated data lines to the controller so generaly it's wise not to mix those drives with other drives on other trays. Best regards Mertol Mertol Ozyoney Storage Practice - Sales Manager Sun Microsystems, TR Istanbul TR Phone +902123352200 Mobile +905339310752 Fax +902123352222 Email mertol.ozyo...@sun.com -----Original Message----- From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-boun...@opensolaris.org] On Behalf Of Bob Friesenhahn Sent: Tuesday, October 13, 2009 10:59 PM To: Nils Goroll Cc: zfs-discuss@opensolaris.org Subject: Re: [zfs-discuss] STK 2540 and Ignore Cache Sync (ICS) On Tue, 13 Oct 2009, Nils Goroll wrote: > > Regarding my bonus question: I haven't found yet a definite answer if there > is a way to read the currently active controller setting. I still assume that > the nvsram settings which can be read with > > service -d <arrayname> -c read -q nvsram region=0xf2 host=0x00 > > do not necessarily reflect the current configuration and that the only way to > make sure the controller is running with that configuration is to reset it. I believe that in the STK 2540, the controllers operate Active/Active except that each controller is Active for half the drives and Standby for the others. Each controller has a copy of the configuration information. Whichever one you communicate with is likely required to mirror the changes to the other. In my setup I load-share the fiber channel traffic by assigning six drives as active on one controller and six drives as active on the other controller, and the drives are individually exported with a LUN per drive. I used CAM to do that. MPXIO sees the changes and does map 1/2 the paths down each FC link for more performance than one FC link offers. 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 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
