Re: Another mkfs.xfs RAID Question

[Seth Mos <knuffie@xxxxxxxxx>]

At 13:00 5-2-2003 +0100, Kai Leibrandt wrote:

> Of course, this is nowhere near a scientific study. It's also
> interesting to see how badly the DAC does in comparison to an ata md
> raid 5, even though there's only one disk per scsi channel in active
> use. Oh and _do_ remember this is mostly focussing on sequential i/o!
> Hope this is interesting to anyone,

3 disk software raid 5 over 2 promise ultra ata 100 controllers. 1 Disk per 
channel.
kernel 2.4.18-19-1.2pre5 , XFS with version 2 logs.
PIII 450 with 256MB ram, 1 Seagate Barracuda IV 80GB, 2 IBM Deathstar 60GXP 
80GB.

No extra mount options given. I can probably get better scores using sunit 
and swidth options.

[root@lsautom raid]# xfs_info /raid
meta-data=/raid                  isize=256    agcount=37, agsize=1048568 blks
data     =                       bsize=4096   blocks=38399936, imaxpct=25
         =                       sunit=8      swidth=16 blks, unwritten=0
naming   =version 2              bsize=4096
log      =internal               bsize=4096   blocks=32768 version=2
         =                       sunit=8 blks
realtime =none                   extsz=65536  blocks=0, rtextents=0

[seth@lsautom seth]$ cat /etc/raidtab
raiddev /dev/md0
        raid-level      5
        nr-raid-disks   3
        nr-spare-disks  0
        persistent-superblock 1
        parity-algorithm        left-symmetric
        chunk-size      32
        device          /dev/hdg1
        raid-disk       0
        device          /dev/hdk1
        raid-disk       1
        device          /dev/hdi2
        raid-disk       2


              -------Sequential Output-------- ---Sequential Input-- 
--Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- 
--Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
          512  5466 89.9 29453 30.2 14302 23.9  5681 94.7 89181 89.1 
216.4  5.0
         1024  5479 90.0 25155 27.5 16346 27.4  5834 97.7 83500 92.5 
192.6  4.2

This is by no means a extremely fast array, but it should give you a 
pointer what to expect from yours.

Cheers

--
Seth
It might just be your lucky day, if you only knew.