Re: [zfs-discuss] Checksum fletcher4 or sha256 ?
On 30/01/2010 09:26, Malte Schirmacher wrote: Mirko wrote: Hi, I'm atmost ready to deploy my new homeserver for final testing. Before I want to be sure that nothing big is left untouched. Reading ZFS Admin Guide About the checksum method, there's no advice about it. The default is fletcher4. there's also SHA256 Now the sha256 is pretty 'heavy' to calculate, so I think that it's left out because can impact the performance in some significative way. right ? You probably want to read http://blogs.sun.com/bonwick/entry/zfs_dedup and also: http://blogs.sun.com/darren/entry/improving_zfs_dedup_performance_via If you aren't doing dedup it almost comes down to wither or not you have the CPU cycles, chances are on a home server you probably do if you are using any recentish Intel or AMD CPU and all you are doing is serving up NAS/iSCSI. If the machine does something else then you may want to choose fletcher4 rather than sha256, but it really depends on how much read and write of data you do etc etc. -- Darren J Moffat ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] Checksum fletcher4 or sha256 ?
Mirko wrote: Hi, I'm atmost ready to deploy my new homeserver for final testing. Before I want to be sure that nothing big is left untouched. Reading ZFS Admin Guide About the checksum method, there's no advice about it. The default is fletcher4. there's also SHA256 Now the sha256 is pretty 'heavy' to calculate, so I think that it's left out because can impact the performance in some significative way. right ? You probably want to read http://blogs.sun.com/bonwick/entry/zfs_dedup ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] Checksum fletcher4 or sha256 ?
Hi, I'm atmost ready to deploy my new homeserver for final testing. Before I want to be sure that nothing big is left untouched. Reading ZFS Admin Guide About the checksum method, there's no advice about it. The default is fletcher4. there's also SHA256 Now the sha256 is pretty 'heavy' to calculate, so I think that it's left out because can impact the performance in some significative way. right ? Is SHA256 a good step-up to guarantee 'correct data' over fletcher4, or it's only marginally better in real life ? I've a C2D 2.8GHz with 4GB, on Gb Eth, is it capable to handler sha256 easy ? 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] Checksum fletcher4 or sha256 ?
On Fri, 29 Jan 2010, Mirko wrote: Is SHA256 a good step-up to guarantee 'correct data' over fletcher4, or it's only marginally better in real life ? The checksum is only used to verify that the data is correct (and not to try to correct it) so fletcher4 is fine. The sha256 algorithm does consume noticeable amounts of CPU, particularly since the checksums are computed when a transaction group is saved. 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
