Date: Sun, 16 Oct 2011 19:17:39 +0300 From: Daniel Kalchev <daniel@digsys.bg> To: "Luchesar V. ILIEV" <luchesar.iliev@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: [ZFS] Using SSD with partitions Message-ID: <169E82FD-3B61-4CAB-B067-D380D69CDED5@digsys.bg> In-Reply-To: <4E9AE725.4040001@gmail.com> References: <CACh33Fpz=uAp8h0Bjsi1Be=ob_94jXtN51mAHvGPkReY5MpTcg@mail.gmail.com> <4E9AE725.4040001@gmail.com>
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On Oct 16, 2011, at 17:16 , Luchesar V. ILIEV wrote: > 6. If, OTOH, you're running a reasonably recent -STABLE (8 or 9), then > your zpool version is likely 28 (thanks, pjd@), which means ZIL is not > that scary, but you might still lose some data. Even an unexpected = power > failure might cause trouble, unless the SSD is designed to handle it > gracefully (this typically involves some sort of capacitor). Just for the record: even without ZIL, you will most definitely lose = data at power outage. In most cases, this will not damage the ZFS = filesystem, but data will be lost. There is nothing that can prevent = this. Therefore, with ZFS v28, adding ZIL does not introduce any more risk to = your data. One thing to have in mind is ZIL will help only under certain workloads, = sequential write is not one of these. It helps most with database-type = loads and sync writes like an NFS server that is written heavily. = Freddie have good advice on determining if it will help. L2ARC on the other hand may help enormously, especially if the spool is = big. Workstation-class motherboards until recently were topped at 8GB = RAM and ZFS is happy with as much RAM as you can offer. Adding L2ARC may = provide more headroom. Benefits of course depend on the workload. = Neither L2ARC or ZIL provide magical benefits. Daniel=
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