Re: IDE-RAID Drive Performance

[Bob]

Nuno Alexandre wrote:

> On Tue, 30 Dec 2003 11:44:01 +0100 
> Mr(s): Nicklas Bondesson wrote:
>
>  
>
> > Hi!
> >
> > I think i'm getting really bad values from my disks. It's two Western
> > Digital WD800JB-00DUA3 (Special Edition 8 MB cache) disks connected to a
> > Promise TX2000 (PDC20271) card (RAID1 using ataraid under Linux 2.4.23).
> >
> > The disks are setup with hdparm at boot time:
> >
> > /sbin/hdparm -X69 -d1 -u1 -m16 -c3 /dev/hda 
> > /sbin/hdparm -X69 -d1 -u1 -m16 -c3 /dev/hdc
> >
> > When running hdparm -tT I get the following:
> >
> > /dev/hda:
> > Timing buffer-cache reads:   128 MB in  1.13 seconds =113.27 MB/sec
> > Timing buffered disk reads:  64 MB in  2.46 seconds = 26.02 MB/sec
> >
> > /dev/hdc:
> > Timing buffer-cache reads:   128 MB in  1.13 seconds =113.27 MB/sec
> > Timing buffered disk reads:  64 MB in  2.47 seconds = 25.91 MB/sec
> >
> > Are these normal values? I don't think so. Please advise.
> >
> > /Nicke
> >    
>
> Hi.
> This is what i get with a Maxtor 6Y120L0 (2MB cache):
>
> /dev/hda:
> Timing buffer-cache reads:   1320 MB in  2.00 seconds = 659.44 MB/sec
> Timing buffered disk reads:  140 MB in  3.02 seconds =  46.40 MB/sec
>
> Using:
> -d1 -u1 -m16 -c3 -W1 -A1 -k1 -X70 -a 8192
>
> I'm not using raid, its a single disk connected to IDE1 on the motherboard.
>
> Maybe you can try those parameters and see if it helps :)
>  
I have two promise cards and four Maxtor
DiamondMax Plus9 60G with 8MB cache each
hdparm -d1 -u1 -m16 -c1 -W1 -A1 -k1 -X70 -a 8192

and my raid0 is software, linux, not the promise chip's raid

on each drive I see 900 MB/s 47.2 MB/s
and on /dev/md/2 /tmp with four drives
four partitions I see 900 MB/s 94 MB/s

that's with 64k raid chunk, reiser 4096b blocks

Linux says 2048k raid chunk would minimize
seek time for better real world performance. It
doesn't work better with hdparm -tT but that's not
realworld. My version of reiserfs doesn't allow
changing the block size.

-Bob D
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