Subject: Re: RaidFrame poor performance
To: Daniel Carosone <>
From: Jochen Keil <>
List: current-users
Date: 01/20/2005 15:13:28

Daniel Carosone wrote:
> To resolve this, if you can, add a fifth disk and choose your stripe
> size and filesystem block size carefully so the filesystem blocks
> exactly map to a full stripe write.  Otherwise, you'd be much better
> off with stripe+mirror over the four disks.

My setup is quite similar to Mihai's. The differences are that it has 
one channel for every disk and i'm using 200gb disks.
I'm satisfied with my performance (~11mb/s on random write) but after 
your email i was wondering if there could be some optimisation.
At the moment i'm doing a benchmark on my 4 disk R5 setup and later i 
will do so on a 3 disk R5. What i'm wondering about is your comment 
about matching stripe size and file system block size.
Default FS block size is 16kb for partitions above 1024MB. I'm using 
this R5 Layout:
  START layout
            # sectPerSU SUsPerParityUnit SUsPerReconUnit RAID_level
            32 1 1 5
I learned that 32 blocks equal to 16KB. As far as i can see my block 
size matches my stripe size so this is the optimum. Am i right here or 
do have to consider various other things too?

Thank you very much in advance and kind regards,

Jochen Keil