Date: Thu, 27 Mar 2014 11:10:48 +0100 From: Joar Jegleim <joar.jegleim@gmail.com> To: krad <kraduk@gmail.com> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: zfs l2arc warmup Message-ID: <CAFfb-hpZos5-d3xo8snU1aVER5u=dSFRx-B-oqjFRTkT83w0Kg@mail.gmail.com> In-Reply-To: <CALfReydi_29L5tVe1P-aiFnm_0T4JJt72Z1zKouuj8cjHLKhnw@mail.gmail.com> References: <CAFfb-hpi20062%2BHCrSVhey1hVk9TAcOZAWgHSAP93RSov3sx4A@mail.gmail.com> <CALfReydi_29L5tVe1P-aiFnm_0T4JJt72Z1zKouuj8cjHLKhnw@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
thnx, I found some similar post over at illumos related to persistent l2arc yesterday. It's interesting :) But it's really not a problem for me how long it takes to warm up the l2arc, if it takes a week that's ok. After all I don't plan on reboot'ing this setup very often + I have 2 servers so I have the option to let the server warmup until i hook it into production again after maintenance / patch upgrade and so on . I'm just curious about wether or not the l2arc warmup itself, or if I would have to do that manual rsync to force l2arc warmup. On 27 March 2014 10:16, krad <kraduk@gmail.com> wrote: > not sure if its made it into freebsd yet but > > https://www.illumos.org/issues/3525 > > > > > On 27 March 2014 07:50, Joar Jegleim <joar.jegleim@gmail.com> wrote: >> >> Hi list ! >> >> I struggling to get a clear understanding of how the l2arc get warm ( >> zfs). >> It's a FreeBSD 9.2-RELEASE server. >> >> From various forum I've come up with this which I have in my >> /boot/loader.conf >> # L2ARC tuning >> # Maximum number of bytes written to l2arc per feed >> # 8MB (actuall=vfs.zfs.l2arc_write_max*(1000 / vfs.zfs.l2arc_feed_min_ms)) >> # so 8MB every 200ms = 40MB/s >> vfs.zfs.l2arc_write_max=8388608 >> # Mostly only relevant at the first few hours after boot >> # write_boost, speed to fill l2arc until it is filled (after boot) >> # 70MB, same rule applys, multiply by 5 = 350MB/s >> vfs.zfs.l2arc_write_boost=73400320 >> # Not sure >> vfs.zfs.l2arc_headroom=2 >> # l2arc feeding period >> vfs.zfs.l2arc_feed_secs=1 >> # minimum l2arc feeding period >> vfs.zfs.l2arc_feed_min_ms=200 >> # control whether streaming data is cached or not >> vfs.zfs.l2arc_noprefetch=1 >> # control whether feed_min_ms is used or not >> vfs.zfs.l2arc_feed_again=1 >> # no read and write at the same time >> vfs.zfs.l2arc_norw=1 >> >> But what I really wonder is how does the l2arc get warmed up ? >> I'm thinking of 2 scenarios: >> >> a.: when arc is full, stuff that evict from arc is put over in l2arc, >> that means that files in the fs that are never accessed will never end >> up in l2arc, right ? >> >> b.: zfs run through fs in the background and fill up the l2arc for any >> file, regardless if it has been accessed or not ( this is the >> 'feature' I'd like ) >> >> I suspect scenario a is what really happens, and if so, how does >> people warmup the l2arc manually (?) >> I figured that if I rsync everything from the pool I want to be >> cache'ed, it will fill up the l2arc for me, which I'm doing right now. >> But it takes 3-4 days to rsync the whole pool . >> >> Is this how 'you' do it to warmup the l2arc, or am I missing something ? >> >> The thing is with this particular pool is that it serves somewhere >> between 20 -> 30 million jpegs for a website. The front page of the >> site will for every reload present a mosaic of about 36 jpegs, and the >> jpegs are completely randomly fetched from the pool. >> I don't know what jpegs will be fetched at any given time, so I'm >> installing about 2TB of l2arc ( the pool is about 1.6TB today) and I >> want the whole pool to be available from the l2arc . >> >> >> Any input on my 'rsync solution' to warmup the l2arc is much appreciated >> :) >> >> >> -- >> ---------------------- >> Joar Jegleim >> Homepage: http://cosmicb.no >> Linkedin: http://no.linkedin.com/in/joarjegleim >> fb: http://www.facebook.com/joar.jegleim >> AKA: CosmicB @Freenode >> >> ---------------------- >> _______________________________________________ >> freebsd-fs@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" > > -- ---------------------- Joar Jegleim Homepage: http://cosmicb.no Linkedin: http://no.linkedin.com/in/joarjegleim fb: http://www.facebook.com/joar.jegleim AKA: CosmicB @Freenode ----------------------
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAFfb-hpZos5-d3xo8snU1aVER5u=dSFRx-B-oqjFRTkT83w0Kg>