Date: Sat, 2 May 2009 14:37:49 -0700 From: Freddie Cash <fjwcash@gmail.com> To: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: current zfs tuning in RELENG_7 (AMD64) suggestions ? Message-ID: <b269bc570905021437h673f97f8l479bd9b20cb2c0cc@mail.gmail.com> In-Reply-To: <ca3526250905021211h4f9139a4xe1b0e429b465c402@mail.gmail.com> References: <E1LzzjJ-0002eV-5A@dilbert.ticketswitch.com> <32A0BDD9-ACF8-43F4-8D2C-0FC151F1D7CB@cryptomonkeys.org> <b269bc570905011628x61105871t5fb0cdbad310ac1c@mail.gmail.com> <ca3526250905021211h4f9139a4xe1b0e429b465c402@mail.gmail.com>
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On Sat, May 2, 2009 at 12:11 PM, Alan Cox <alan.l.cox@gmail.com> wrote: > On Fri, May 1, 2009 at 6:28 PM, Freddie Cash <fjwcash@gmail.com> wrote: >> On Fri, May 1, 2009 at 4:12 PM, Louis Kowolowski >> <louisk@cryptomonkeys.org> wrote: >> > On May 1, 2009, at 1:53 PM, Pete French wrote: >> >> ... >> >> The tuning isn't there to improve performance, it's there to prevent >> >> the box going titus due to a panic when the ARC gets too big, and >> >> you are missing the mian one, which is to limit the size of the ARC. >> >> On recent versions of BSD (and you are running 7.2, so thats fine) th= en >> >> the defaults for kmem size are fine, but you still need something lik= e >> >> this: >> >> >> >> vfs.zfs.arc_max=3D"256M" >> >> >> >> In there to stop the ARC growing. thats the only tuning I have on >> >> my 4 gig machine, which takes a steady stream of data and is used >> >> for taking backup snapshots. ZFS is excellent, and for me is perfectl= y >> >> stable, to the point where I am starting to roll it out to production >> >> machines, with the above tuning. >> >> >> > I agree, although I'm using 384 instead of 256. =C2=A0My systems have = been >> > running in production for almost a year now w/o any ZFS issues. >> >> The exact value to use will depend on the system. =C2=A0Particularly on = the >> amount of RAM in the system, and what kmem_max is set to. =C2=A0A >> "rule-of-thumb" we've been using is: >> =C2=A0 kmem_max should be half of the amount of RAM (or 1.5 GB as that's >> the current max) > > This information is outdated.=C2=A0 The current max in RELENG_7 for amd64= is > ~3.75GB. Nice! Good to hear. Thanks for the correction. Looking forward to testing this with 7.2. --=20 Freddie Cash fjwcash@gmail.com
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