Are there any drawbacks to partition a SSD in two parts and use L2ARC on one partition, and ZIL on the other? Any thoughts? -- This message posted from opensolaris.org
On Wed, 2010-07-21 at 09:42 -0700, Orvar Korvar wrote:> Are there any drawbacks to partition a SSD in two parts and use L2ARC on one partition, and ZIL on the other? Any thoughts?Its probably a reasonable approach. The ZIL can be fairly small... only about 8 GB is probably sufficient for most typical uses. (Even 4GB would be a win in most cases. :-) - Garrett
Ok, so the bandwidth will be cut in half, and some people use this configuration. But, how bad is it to have the bandwidth cut in half? Will it hardly notice? (Just ordinary home server, some media files, ebooks, etc) -- This message posted from opensolaris.org
----- Original Message -----> On Wed, 2010-07-21 at 09:42 -0700, Orvar Korvar wrote: > > Are there any drawbacks to partition a SSD in two parts and use > > L2ARC on one partition, and ZIL on the other? Any thoughts? > > Its probably a reasonable approach. The ZIL can be fairly small... > only > about 8 GB is probably sufficient for most typical uses. (Even 4GB > would be a win in most cases. :-)Half of RAM is maximum, and unless you have write intensive jobs, 1GB will probably suffice for most use, but then, it depends on your workload. The ZIL is flushed every, what, 10 seconds?, so if you have >1GB writes per 10 seconds, you want >1GB SLOG. At least, that''s theory. Vennlige hilsener / Best regards roy -- Roy Sigurd Karlsbakk (+47) 97542685 roy at karlsbakk.net http://blogg.karlsbakk.net/ -- I all pedagogikk er det essensielt at pensum presenteres intelligibelt. Det er et element?rt imperativ for alle pedagoger ? unng? eksessiv anvendelse av idiomer med fremmed opprinnelse. I de fleste tilfeller eksisterer adekvate og relevante synonymer p? norsk.
On 07/22/10 04:00, Orvar Korvar wrote:> Ok, so the bandwidth will be cut in half, and some people use this > configuration. But, how bad is it to have the bandwidth cut in half? > Will it hardly notice?For a home server, I doubt you''ll notice. I''ve set up several systems (desktop & home server) as follows: - two large conventional disks, mirrored, as data pool. - single X25-M, 80GB, divided in three slices: 50% in slice 0 as root pool, (with dedup & compression enabled, and copies=2 for rpool/ROOT) 1GB in slice 3 as ZIL for data pool remainder in slice 4 as L2ARC for data pool. two conventional disks + 1 ssd performs much better than two disks alone. If I needed more space (I haven''t, yet), I''d add another mirror pair or two to the data pool. I''ve been very happy with the results. - Bill
On Wed, Jul 21, 2010 at 12:42 PM, Orvar Korvar < knatte_fnatte_tjatte at yahoo.com> wrote:> Are there any drawbacks to partition a SSD in two parts and use L2ARC on > one partition, and ZIL on the other? Any thoughts? > -- > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss >It''s not going to be as good as having separate but i can tell you that i did this on my home system and it was WELL worth it. I used one of the sandforce 1500 based SSD''s 50 gb i used 9 gb for ZIL, and the rest for L2ARC. adding the zil gave me about 400-500% nfs write performance. Seeing as you can''t ever use more than half your ram for ZIL anyways, the only real downside to doing this is that i/o becomes split between zil and L2arc but realistically it depends on your workload....for mine, i noticed a HUGE benefit from doing this. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100723/0ae54819/attachment.html>