Re: striping of a 4 drive raid10

["Keld Jørn Simonsen" <keld@dkuug.dk>]

On Mon, Jan 28, 2008 at 07:13:30AM +1100, Neil Brown wrote:
> On Sunday January 27, keld@dkuug.dk wrote:
> > Hi
> > 
> > I have tried to make a striping raid out of my new 4 x 1 TB
> > SATA-2 disks. I tried raid10,f2 in several ways:
> > 
> > 1: md0 = raid10,f2 of sda1+sdb1, md1= raid10,f2 of sdc1+sdd1, md2 = raid0
> > of md0+md1
> > 
> > 2: md0 = raid0 of sda1+sdb1, md1= raid0 of sdc1+sdd1, md2 = raid01,f2
> > of md0+md1
> > 
> > 3: md0 = raid10,f2 of sda1+sdb1, md1= raid10,f2 of sdc1+sdd1, chunksize of 
> > md0 =md1 =128 KB,  md2 = raid0 of md0+md1 chunksize = 256 KB
> > 
> > 4: md0 = raid0 of sda1+sdb1, md1= raid0 of sdc1+sdd1, chunksize
> > of md0 = md1 = 128 KB, md2 = raid01,f2 of md0+md1 chunksize = 256 KB
> > 
> > 5: md0= raid10,f4 of sda1+sdb1+sdc1+sdd1
> 
> Try
>   6: md0 = raid10,f2 of sda1+sdb1+sdc1+sdd1

That I already tried, (and I wrongly stated that I used f4 in stead of
f2). I had two times a thruput of about 300 MB/s but since then I could
not reproduce the behaviour. Are there errors on this that has been
corrected in newer kernels?


> Also try raid10,o2 with a largeish chunksize (256KB is probably big
> enough).

I tried that too, but my mdadm did not allow me to use the o flag.

My kernel is 2.6.12  and mdadm is v1.12.0 - 14 June 2005.
can I upgrade the mdadm alone to a newer version, and then which is
recommendable?

best regards
keld