Thomas, On Jul 4, 2011, at 9:53 AM, Thomas Nau wrote:
> Richard > > > On 07/04/2011 03:58 PM, Richard Elling wrote: >> On Jul 4, 2011, at 6:42 AM, Lanky Doodle wrote: >> >>> Hiya, >>> >>> I''ve been doing a lot of research surrounding this and ZFS, including some >>> posts on here, though I am still left scratching my head. >>> >>> I am planning on using slow RPM drives for a home media server, and it's >>> these that seem to 'suffer' from a few problems; >>> >>> Seagate Barracuda LP - Looks to be the only true 512b sector hard disk. >>> Serious firmware issues >>> Western Digital Cavier Green - 4K sectors = crap write performance >>> Hitachi 5K3000 - Variable sector sizing (according to tech. specs) >>> Samsung SpinPoint F4 - Just plain old problems with them >>> >>> What is the best drive of the above 4, and are 4K drives really a no-no >>> with ZFS. Are there any alternatives in the same price bracket? >> >> 4K drives are fine, especially if the workload is read-mostly. >> >> Depending on the OS, you can tell ZFS to ignore the incorrect physical >> sector >> size reported by some drives. Today, this is easiest in FreeBSD, a little >> bit more >> tricky in OpenIndiana (patches and source are available for a few different >> implementations). Or you can just trick them out by starting the pool with a >> 4K >> sector device that doesn't lie (eg, iscsi target). > > Are you refering to the "ahift" patches and what do you mean by tricking them > by using an iscsi target? This is a roundabout way to do this, but it can be done without changing any source :-) With the Nexenta or Solaris iSCSI target, you can set the blocksize for a LUN. When you create the pool for the first time, make one of the devices be an iSCSI LUN with a 4KB block size. This will cause the top-level vdev to use ashift=12. You can then replace the iSCSI LUN with a different device using "zpool replace" -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
