Date: Thu, 30 Jul 2015 10:41:19 -0400 From: Paul Kraus <paul@kraus-haus.org> To: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: ZFS on 10-STABLE r281159: programs, accessing ZFS pauses for minutes in state [*kmem arena] Message-ID: <26DA7547-3258-44CC-A3EA-338AFA13640E@kraus-haus.org> In-Reply-To: <55BA0F41.6070508@multiplay.co.uk> References: <164833736.20150730143008@serebryakov.spb.ru> <55BA0F41.6070508@multiplay.co.uk>
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On Jul 30, 2015, at 7:49, Steven Hartland <killing@multiplay.co.uk> wrote: > On 30/07/2015 12:30, Lev Serebryakov wrote: >> >> Deduplication IS TURNED OFF. atime is turned off. Record size set to 1M as >> I have a lot of big files (movies, RAW photo from DSLR, etc). Compression is >> turned off. > You don't need to do that as record set size is a min not a max, if you don't force it large files will still be stored efficiently. Can you point to documentation for that ? I really hope that the 128KB default is not a minimum record size or a 1KB file will take up 128 KB of FS space. As far as I know, zfs recordsize has always, since the very beginning of ZFS under Solaris, been the MAX recrodsize, but it is also a hint and not a fixed value. ZFS will write any size records (powers of 2) from 512 bytes (4 KB in the case of an shift = 4 pool) up to recordsize. Tuning of recordsize has been frowned upon since the beginning unless you _know_ the size of your writes and they are fixed (like 8 KB database records). Also note that ZFS will fit the write to the pool in the case of RAIDz<n>, see Matt Ahrens bloig entry here: http://blog.delphix.com/matt/2014/06/06/zfs-stripe-width/ -- Paul Kraus paul@kraus-haus.orghelp
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