Looks like my RAID5 arrays have crap performance - esp. the master
array.

Is it something to do with the master/slave thing, or something else?

Comments?

Max.

/dev/md0 is 2xWD2000 SATA via m/b - RAID0
=========================================
      ------Sequential Output------ --Sequential Input- --Random-
      -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
 Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
   3G 49056  88 136360  33 38863  10 52577  88 115880  16 389.6   1
      ------Sequential Create------ --------Random Create--------
      -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
   16  2213  24 +++++ +++  6623  73  7286  67 +++++ +++  5289  57

/dev/md1 is 4xWD800 PATA RAID5 master array
===========================================
      ------Sequential Output------ --Sequential Input- --Random-
      -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
 Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
   3G 31272  59 34758   8  9009   3 16343  28 19788   3 265.3   1
      ------Sequential Create------ --------Random Create--------
      -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
   16   506   8 +++++ +++   574   7   530  10 +++++ +++   367   5

/dev/md2 is 4xWD2000 PATA RAID5 slave array
===========================================
      ------Sequential Output------ --Sequential Input- --Random-
      -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
 Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
   3G 44201  78 43174  11 14761   6 38522  67 66666  14 359.4   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  1098  14 +++++ +++  1131  16  1118  17 +++++ +++  1006  15


Max Waterman wrote:
Hi,

So, I did try this (two RAIDs, one as all master devices and one as all slaves devices) and it seems to work OK.

I had a bit of a problem making the slave plugs reach the drives. With all the drives as master devices, I got the full one meter length and there was no problem, but the slave plug is not the full length and so was a struggle. Far from ideal, but I'm short of cash, so I had to try.

What I am not sure about is the performance. I have run bonnie++ on the arrays (plus another 2x250GB RAID0 array, running off the motherboard SATA controller), but haven't really looked at the results. I'll post them here tonight.

BTW, I was considering trading in my EIDE drives for 8xWD2000 SATA drives and getting a Supermicro 8-port SATA controller :

http://www.supermicro.com/products/accessories/addon/DAC-SATA-MV8.cfm

It looks like just the job. Just thought I'd mention that board in case other people have been looking for something similar. They tell me it works on PCI as well as PCI-X.

Max.

Paul Barker wrote:

Hi

I'll give it a try since the alternative (two 4 channel s/w RAID boards)

yet is more money ;)

Cool, let me know how you get on. I'd be interested if it works !
Cheers
Paul



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