Date: Fri, 16 Sep 2011 23:22:30 +0200 From: Terje Elde <terje@elde.net> To: "freebsd@top-consulting.net" <freebsd@top-consulting.net> Cc: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: FS of choice for max random iops ( Maildir ) Message-ID: <D0FD7882-E1F6-45C4-B3BE-58E046401699@elde.net> In-Reply-To: <20110916101833.17485ybnq5srjbc4@mail.top-consulting.net> References: <20110916063153.200375qdq59crf8c@mail.top-consulting.net> <32990703-D068-4B0D-AF3A-C1E6EA0A4100@elde.net> <20110916101833.17485ybnq5srjbc4@mail.top-consulting.net>
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On 16. sep. 2011, at 16:18, freebsd@top-consulting.net wrote: > Got a measly 74MB/sec. You can't ask for advice, get it, do something completely different, and the= n complain that it didn't work.=20 Neither can you ask people to donate their time, if you won't spend yours.=20= In other words: if you won't listen, there's no point in us talking.=20 However: Don't disable ZIL. Just don't. It's not the way to go. If you want to know w= hy, google will help.=20 Also, you're making some assumptions, such as the ZIL being bad for performa= nce. That's not always the case. ZIL-writes are a rather nice load for spinn= ing metal storage. Even if you write through cache, that can give you a boos= t on your real world workload.=20 Which brings us to the third bit. You're benchmarking, not trying real world= loads. That's the load you'll have to worry about, and it's the load zfs sh= ines at.=20 Thanks to the ZIL (the thing you're trying to kill, remember?) you can conve= rt seek heavy writes to sequential zil-writes, freeing up disk bandwith for c= oncurrent reads.=20 If you want to test before spending money, try what Svein said. Set up a sma= ll logical volume (preferrably smaller than your controller cache, if it's l= arge enough), then try that as a dedicated zil-device.=20 Never tried that, but worth a shot.=20 Terje=
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