Date: Wed, 17 Jan 2007 00:57:05 +0100 From: Ivan Voras <ivoras@fer.hr> To: "Wood, Russell" <Russell.Wood@rac.com.au> Cc: freebsd-performance@freebsd.org, freebsd-questions@freebsd.org Subject: Re: Very Poor Raid Card Performance Message-ID: <45AD6651.5010107@fer.hr> In-Reply-To: <D6B5375CBC761B4BAD78E414B4BB557266318C@mercury.rac.com.au> References: <D6B5375CBC761B4BAD78E414B4BB557266318C@mercury.rac.com.au>
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Wood, Russell wrote:
> I have an LSI MegaRaid with three drives at RAID 5: works a
> god-damn-treat. I don't know what my throughput is on RAID 5 but RAID 0=
> was fast (70MB/s+).
Mine was RAID5. Hmm, oops, it wasn't LSI but HP/Compaq CISS, battery
backed, SATA on SAS.
da0 at ciss0 bus 0 target 0 lun 0
da0: <COMPAQ RAID 5 VOLUME OK> Fixed Direct Access SCSI-0 device
da0: 135.168MB/s transfers
da0: 476886MB (976662896 512 byte sectors: 255H 32S/T 65535C)
> Were you doing these tests a few hours after initializing the array, by=
> any chance? If so, then the poor performance could be because the array=
> was `in build' while you were using it, and therefore you'd get very
> poor performance.
Yes, I observed BIOS status. Here's a typical run of bonnie++:
Version 1.93c ------Sequential Output------ --Sequential Input-
--Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
xxx.com 2500M 358 99 13446 4 7068 2 559 96 97548 23
300.0 10
Latency 23236us 848ms 488ms 191ms 214ms
175ms
My reading of iostat during 'dd' is that writes perform good until the
on-controller cache gets filled, then it slows down:
tty da0 pass0 cpu
tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id
=2E..
0 60 0.00 0 0.00 0.00 0 0.00 0 0 0 0 100
1 64 127.93 217 27.08 0.00 0 0.00 0 0 5 0 95
0 61 125.92 400 49.14 0.00 0 0.00 0 0 2 1 98
0 61 128.00 107 13.36 0.00 0 0.00 0 0 2 0 98
0 61 128.00 107 13.36 0.00 0 0.00 0 0 2 0 98
0 61 128.00 104 12.99 0.00 0 0.00 0 0 2 0 98
Cache size is 128MB, 75% dedicated to write caching.
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