2.4.22 + RAID 1 + SATA + 2 disks => no maximum speed

From: Catalin BOIE (util_at_deuroconsult.ro)
Date: 09/05/03

  • Next message: Q=DA=B2=A8?=: "CF GPRS-MODEM card on Intel HCCCBCTA1/Cotulla Platform,problem with serial port" 
    Date:	Fri, 5 Sep 2003 08:01:31 +0300 (EEST)
To: linux-raid@vger.kernel.org

    Hi!

    I have a machine with 2 SATA disks on 2 separate buses.
    hdparm -t /dev/hda reports 50MB/s
    hdparm -t /dev/hdb reports 50MB/s

    I created a raid1 array with hda3 and hdc3, same partition sizes.

    If I do hdparm -t /dev/md0 it reports 50MB/s

    If I do cat /dev/md0 > /dev/null, vmstat reports 50MB/s
    If I start another cat /dev/md0 > /dev/null, in another console, I get
    100MB/s from vmstat.

    Why I don't get 100MB/s on a single cat command?

    Some other test:
    cat /dev/hda3 > /dev/null&
    cat /dev/hdc3 > /dev/null&
    vmstat shows 100MB/s.

    Also, seems that writing is very slow (8MB/s).

    Any ideas?

    Thank you very much! 

    ---
Catalin(ux) BOIE
catab@deuroconsult.ro
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