Date: Tue, 15 Jan 2013 15:28:56 -0500 From: Karim Fodil-Lemelin <fodillemlinkarim@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: IBM blade server abysmal disk write performances Message-ID: <50F5BC08.1060700@gmail.com> In-Reply-To: <CAA3ZYrACHLU-4OyhLdD%2BmfCDR_kubBg-AiVcopL-skqDurE7YA@mail.gmail.com> References: <CAA3ZYrACHLU-4OyhLdD%2BmfCDR_kubBg-AiVcopL-skqDurE7YA@mail.gmail.com>
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On 15/01/2013 3:03 PM, Dieter BSD wrote: > Disabling the disks's write cache is *required* for data integrity. > One op per rev means write caching is disabled and no queueing. > But dmesg claims "Command Queueing enabled", so you should be getting > more than one op per rev, and writes should be fast. > Is this dd to the raw drive, to a filesystem? (FFS? ZFS? other?) > Are you running compression, encryption, or some other feature > that might slow things down? Also, try dd with a larger block size, > like bs=1m. Hi, Thanks to everyone that answered so far. Here is a follow up. dd to the raw drive and no compression/encryption or some other features, just a naive boot off a live 9.1 CD then dd (see below). The following results have been gathered on the FreeBSD 9.1 system: # dd if=/dev/zero of=toto count=100 100+0 records in 100+0 records out 51200 bytes transferred in 1.057507 secs (48416 bytes/sec) # dd if=/dev/zero of=toto count=100 bs=104 100+0 records in 100+0 records out 10400 bytes transferred in 1.209524 secs (8598 bytes/sec) # dd if=/dev/zero of=toto count=100 bs=1024 100+0 records in 100+0 records out 102400 bytes transferred in 0.844302 secs (121284 bytes/sec) # dd if=/dev/zero of=toto count=100 bs=10240 100+0 records in 100+0 records out 1024000 bytes transferred in 2.173532 secs (471123 bytes/sec) # dd if=/dev/zero of=toto count=100 bs=102400 100+0 records in 100+0 records out 10240000 bytes transferred in 19.915159 secs (514181 bytes/sec) # dd if=/dev/zero of=toto count=100 100+0 records in 100+0 records out 51200 bytes transferred in 1.070473 secs (47829 bytes/sec) # dd if=/dev/zero of=foo count=100 100+0 records in 100+0 records out 51200 bytes transferred in 0.683736 secs (74883 bytes/sec) # dd if=/dev/zero of=foo count=100 bs=1024 100+0 records in 100+0 records out 102400 bytes transferred in 0.682579 secs (150019 bytes/sec) # dd if=/dev/zero of=foo count=100 bs=10240 100+0 records in 100+0 records out 1024000 bytes transferred in 2.431012 secs (421224 bytes/sec) # dd if=/dev/zero of=foo count=100 bs=102400 100+0 records in 100+0 records out 10240000 bytes transferred in 19.963030 secs (512948 bytes/sec) # dd if=/dev/zero of=foo count=10 bs=1024000 10+0 records in 10+0 records out 10240000 bytes transferred in 19.615134 secs (522046 bytes/sec) # dd if=/dev/zero of=foo count=1 bs=10240000 1+0 records in 1+0 records out 10240000 bytes transferred in 19.579077 secs (523007 bytes/sec) Best regards, Karim.
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