[zfs-discuss] 512b vs 4K sectors
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? Who would have thought choosing a hard disk could be so 'hard'! Thanks -- This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] 512b vs 4K sectors
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). Who would have thought choosing a hard disk could be so 'hard'! I recommend enterprise-grade disks, none of which made your short list ;-(. -- richard I'm going through this at the moment. I've bought a pair of Seagate Barracuda XT 2Tb disks (which are a bit more Enterprise than the list above), just plugged them in, and so far they're OK. Not had them long enough to report on longevity. -- Andrew Gabriel ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] 512b vs 4K sectors
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? Thanks, Thomas ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] 512b vs 4K sectors
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
Re: [zfs-discuss] 512b vs 4K sectors
On Mon, Jul 04, 2011 at 01:11:09PM -0700, Richard Elling wrote: Thomas, On Jul 4, 2011, at 9:53 AM, Thomas Nau wrote: 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 Thomas, I wrote a little more detailed recipe for this a month or two ago, look in the archives. -- Dan. pgprf8LqI8Q2t.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
