Re: looking for a transparent hardware RAID controller for debian
On 11/10/05, Ron Johnson <ron.l.johnson@cox.net> wrote:
> The issue was performance, though. Are you getting good speed?
I must have missed that email then, sorry about that. We use RAID5 on
this Linux box, RAID5 on FreeBSD (old driver) and RAID1 and 10 on
FreeBSD (old and new driver). Overall our impression has been that the
RAIDs are reasonably fast, but not as fast as 15k RPM SCSI drives,
specifically with random access. MySQL databases seem to perform much
better on single fast SCSI disks than on 7200RPM SATA RAIDs, at this
time, for us.
The added reliability and reduced concern over total data loss is
worth the reduced speed for most applications -- especially web
servers. (Of course, data loss is still possible, but restores of this
magnitude take a long time, so anything to avoid that is a big win.)
Specifically regarding the RAID5 server mentioned previously, which is
a dual 2.8Ghz Xeon 2MB cache w/ 4GB RAM 3ware 9500S-12 2.6.13.2 kernel
(for the archives), and /data2-2 being one of the auto-carved "slices"
of the larger RAID, here's the output of a 'dd' command:
$ dd if=/dev/zero of=/data2-2/bigfile bs=131072 count=100000
100000+0 records in
100000+0 records out
13107200000 bytes transferred in 119.269480 seconds (109895675 bytes/sec)
and bonnie++ -d /data2-2/tmp -s 1024m -u nobody:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
-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
raid 8G 40076 99 93772 18 29379 6 29792 68 185058 18 314.2 0
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 4043 20 +++++ +++ 2964 14 3603 18 +++++ +++ 2024 9
raid,8G,40076,99,93772,18,29379,6,29792,68,185058,18,314.2,0,16,4043,20,+++++,+++,2964,14,3603,18,+++++,+++,2024,9
Note that this server is actually in active (but light) production use
while running these commands.
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