Date: Thu, 27 Mar 2014 21:34:11 +0100 From: Joar Jegleim <joar.jegleim@gmail.com> To: Rainer Duffner <rainer@ultra-secure.de> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: zfs l2arc warmup Message-ID: <CAFfb-hriWXeu6EMq9b-V9gqqXGVXBS2Dfk7ymTGfxb17qqNvVw@mail.gmail.com> In-Reply-To: <20140327114018.6d50b666@suse3.ewadmin.local> References: <CAFfb-hpi20062%2BHCrSVhey1hVk9TAcOZAWgHSAP93RSov3sx4A@mail.gmail.com> <20140327114018.6d50b666@suse3.ewadmin.local>
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> Don't you need RAM for the L2ARC, too? > > http://www.richardelling.com/Home/scripts-and-programs-1/l2arc > > > I'd just max-out the RAM on the DL370 - you'd need to do that anyway, > according to the above spread-sheet.... > yeah, it does. At the moment I've got 2x480GB ssd for l2arc and 144GB ram, though I haven't found a way to calculate if I have enough ram or not I've seen posts that make me suspect I had enough ram for this setup. The link from Johan Hendriks https://blogs.oracle.com/brendan/entry/l2arc_screenshots mention that in the bottom actually " It costs some DRAM to reference the L2ARC, at a rate proportional to record size. For example, it currently takes about 15 Gbytes of DRAM to reference 600 Gbytes of L2ARC - at an 8 Kbyte ZFS record size. If you use a 16 Kbyte record size, that cost would be halve - 7.5 Gbytes. This means you shouldn't, for example, configure a system with only 8 Gbytes of DRAM, 600 Gbytes of L2ARC, and an 8 Kbyte record size - if you did, the L2ARC would never fully populate. " My two 480GB ssd's will probably be full by tomorrow, they're currently at 686GB and got about 207GB left to fill. I wonder how I can read out how much ram is used for l2arc reference (?) would that be the 'HEADER' value from top in 9.2-RELEASE (the ARC line) it was around 3GB yesterday and now I see it's climbed to about 6.3GB . (got 128KB record size) . On 27 March 2014 11:40, Rainer Duffner <rainer@ultra-secure.de> wrote: > Am Thu, 27 Mar 2014 08:50:06 +0100 > schrieb Joar Jegleim <joar.jegleim@gmail.com>: > >> Hi list ! >> >> I struggling to get a clear understanding of how the l2arc get warm >> ( zfs). It's a FreeBSD 9.2-RELEASE server. >> > >> 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 :) >> >> > > > > Don't you need RAM for the L2ARC, too? > > http://www.richardelling.com/Home/scripts-and-programs-1/l2arc > > > I'd just max-out the RAM on the DL370 - you'd need to do that anyway, > according to the above spread-sheet.... > > > > > -- ---------------------- Joar Jegleim Homepage: http://cosmicb.no Linkedin: http://no.linkedin.com/in/joarjegleim fb: http://www.facebook.com/joar.jegleim AKA: CosmicB @Freenode ----------------------
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