Date: Wed, 28 Mar 2007 08:42:51 -0500 From: Eric Anderson <anderson@freebsd.org> To: =?ISO-8859-1?Q?Szab=F3_P=E9ter?= <matyee@mail.alba.hu> Cc: "R. B. Riddick" <arne_woerner@yahoo.com>, freebsd-geom@freebsd.org Subject: Re: raid3 is slow Message-ID: <460A70DB.6030808@freebsd.org> In-Reply-To: <657228.54534.qm@web30313.mail.mud.yahoo.com> References: <657228.54534.qm@web30313.mail.mud.yahoo.com>
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On 03/28/07 08:21, R. B. Riddick wrote: > --- Szabó Péter <matyee@mail.alba.hu> wrote: >> raid3 >> Transfer rates: >> outside: 102400 kbytes in 1.179933 sec = 86785 kbytes/sec >> middle: 102400 kbytes in 1.148816 sec = 89135 kbytes/sec >> inside: 102400 kbytes in 1.171987 sec = 87373 kbytes/sec >> > Looks good... It's about right, I agree. >> #diskinfo -vt /dev/label/nmivol1 >> outside: 102400 kbytes in 1.839020 sec = 55682 kbytes/sec >> middle: 102400 kbytes in 2.112483 sec = 48474 kbytes/sec >> inside: 102400 kbytes in 3.416896 sec = 29969 kbytes/sec >> > Looks slow... You think so? I think that's pretty acceptable for a UDMA100 device. >> # atacontrol mode ad0 >> current mode = UDMA100 >> # atacontrol mode ad1 >> current mode = UDMA100 >> # atacontrol mode ad2 >> current mode = UDMA100 >> # atacontrol mode ad3 >> current mode = UDMA100 >> # atacontrol mode ad6 >> current mode = SATA150 >> > Looks good... > >> gstripe may help, and extends disk space, but less secure. >> > Yup... > >> #dd if=/dev/zero of=/mnt/new/x.x bs=1m count=128 >> 128+0 records in >> 128+0 records out >> 134217728 bytes transferred in 11.410957 secs (11762180 bytes/sec) >> > Hmm That looks pretty poor to me. Can you send the output of a df -ik /mnt? > And what if u try this: > dd if=/dev/raid3/... of=/dev/null bs=1m count=128 > ? > >>> Disks ad0 ad1 ad2 ad3 ad6 intrn >>> KB/t 8.42 8.42 8.42 8.42 5.67 113904 buf >>> tps 287 287 287 287 1780 133 dirtybuf >>> MB/s 2.36 2.36 2.36 2.36 9.85 69984 desiredvnodes >>> % busy 25 26 24 26 99 21586 numvnodes > 8KB/transfer is a little low for my taste... Looks like ur copy program uses > 32KB transfers, instead of 128KB transfers... > >>> I use mc to copy. > What if u try > dd if=/source-file/on/raid3-device of=/dev/null bs=1m count=128 > ? It seems that the write speed is the real issue possibly. A great test would be to write to the device itself, but that would blast the filesystem. If that's ok, this would be a good test: dd if=/dev/zero of=/dev/raid3/... bs=1m count=512 Eric
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