RAIDframe performance (RAID-5)

[Johan Ihren <johani%johani.org@localhost>]

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Hi,

I just configured a 150GB RAID-5 out of 3 75GB components (one half of  
a reasonably modern 160GB disk each). Write performance suck badly. So  
I ran bonnie++ on each of

* the RAID-5
* a RAID-1 set made out of the other half of the  same three disks (w/  
one spare).
* one of the raw disks

Results are basically that RAID-1 and raw disk are comparable at  
roughly 40+GB/s read and write each while the RAID-5 has double read  
perfomance (that's mostly expected) while only 20% of the write  
performance (i.e. < 10GB/s writes). I realise that there's a cost to  
having to recompute the parity, but 80% is way more than I expected.

Is this what I should expect or have I fumbled somewhere?

I've used RAIDframe quite extensively before, but usually as RAID-1,  
except for one case where I used a RAID-5, but I cannot test the  
performance of that one because it broke down recently (I'll get to  
that shortly, but in a separate message). But the result is that I  
have no RAID-5s to compare performance with.

Regards,

Johan
- ---------------------
Raw bonnie++ results:

RAID5 w/ following parameters:
* START layout
* # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level_1
* 128 1 1 5

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
pear           300M  9802   4  9619   3  7356   2 89596  68 97834  15  
468.5   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   453  22 +++++ +++  1152   4   462  22  2404   
99   800  17
pear,300M,9802,4,9619,3,7356,2,89596,68,97834,15,468.5,1,16,453,22,++++ 
+,+++,1152,4,462,22,2404,99,800,17

RAID1 w/ following parameters:
* START layout
* # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level_1
* 128 1 1 1

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
pear           300M 43556  20 46224  16 15820   4 43234  32 43707   7  
424.4   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   702  35 +++++ +++  2335   9   774  38  2416   
99  1596  36
pear,300M, 
43556,20,46224,16,15820,4,43234,32,43707,7,424.4,1,16,702,35,+++++,+++, 
2335,9,774,38,2416,99,1596,36

Raw disk, no RAIDframe at all:

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
pear           300M 47866  24 48609  17 22297   7 44870  34 46183   8  
305.2   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   932  54 +++++ +++  3439  25   954  55  2417   
99  1973  51
pear,300M, 
47866,24,48609,17,22297,7,44870,34,46183,8,305.2,1,16,932,54,+++++,+++, 
3439,25,954,55,2417,99,1973,51
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