Re: [PATCH] Marvell SATA fixes v2

[Bogdan Costescu <Bogdan.Costescu@iwr.uni-heidelberg.de>]

On Wed, 23 Nov 2005, Jeff Garzik wrote:

> > 1. several badblocks tests finished fine; the speed is also fine (about 
> > 50Mbytes/s both read and write as reported by both iostat during badblocks 
> > and bonnie++ on an ext2 FS).
> cool

... and it's getting even cooler: with 4 WD Raptor 74GB, I get about 
65MB/s per disk up to 3 disks accessed simultaneously; only when also 
using the 4th disk, the speed per disk decreases to about 50MB/s. 
Given than 3*65 ~ 4*50, I might reach some hidden limit, but it's 
already quite good. So I'd appreciate if people with similar hardware 
could test this, to see if there's a limit in the controller or in my 
system ;-)

I have to mention that the above figures were obtained not with RAID0, 
but with individual reading from each drive. RAID0 somehow made reads 
slower, I got only 120-130 MB/s total speed; writes over RAID0 were as 
expected about 200MB/s (I only tried RAID0 with 128k and 1024k chunk 
sizes).

When creating the array (with mdadm --create), I got these messages 
which I haven't seen before, although I played with SATA and RAID0 
with some older kernels:

ata4: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
ata4: status=0xd0 { Busy }
ata3: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
ata3: status=0xd0 { Busy }
ata2: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
ata2: status=0xd0 { Busy }
ata1: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
ata1: status=0xd0 { Busy }

(in this order, although the order specified on the mdadm command line 
was the opposite).

--
Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu@IWR.Uni-Heidelberg.De
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