WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

RE: [Xen-users] Very slow drives, I/O - DMA issues?

To: "'Lonny Selinger'" <lonny@xxxxxxxxxxxxxxxxxxxxxxxx>, <burke@xxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Very slow drives, I/O - DMA issues?
From: "Steffen Heil" <lists@xxxxxxxxxxxxxxx>
Date: Wed, 21 Feb 2007 21:33:08 +0100
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Delivery-date: Wed, 21 Feb 2007 12:32:12 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <28571.204.83.191.12.1172075595.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <39120.24.89.80.126.1172011081.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><59303.24.89.80.126.1172012088.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><37633.24.89.80.126.1172017931.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><6d06ce20702201754q256119bdnb4124106572136e7@xxxxxxxxxxxxxx> <35464.24.89.80.126.1172055525.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><19542.204.83.191.12.1172064603.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><19559.204.83.191.12.1172064691.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><6d06ce20702210753k27fdec7v830820d5cb144f12@xxxxxxxxxxxxxx> <27188.204.83.191.12.1172073849.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx><36062.199.46.199.233.1172074440.squirrel@xxxxxxxxxxxxxxxxxxxxx> <28571.204.83.191.12.1172075595.squirrel@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcdV1hjA+aEiKXMWRn2Am9sbatmFzAAIRH9g
Hello.

I saw your post:
> /dev/hda:
>  Timing cached reads:   1380 MB in  2.00 seconds = 689.47 MB/sec
>  Timing buffered disk reads:  142 MB in  3.02 seconds =  47.02 MB/sec
> 
> /dev/hdb:
>  Timing cached reads:   1452 MB in  2.00 seconds = 725.20 MB/sec
>  Timing buffered disk reads:  138 MB in  3.02 seconds =  45.68 MB/sec

I wondered about hdparm -tT, which I didn't know.
So I tries it myself:

>hdparm -tT /dev/hd?

/dev/hda:
 Timing cached reads:   266 MB in  2.00 seconds = 132.84 MB/sec
 Timing buffered disk reads:  144 MB in  3.01 seconds =  47.82 MB/sec

/dev/hdb:
 Timing cached reads:   490 MB in  2.00 seconds = 244.92 MB/sec
 Timing buffered disk reads:  164 MB in  3.01 seconds =  54.48 MB/sec

/dev/hdc:
 Timing cached reads:   506 MB in  2.00 seconds = 252.41 MB/sec
 Timing buffered disk reads:   50 MB in  3.02 seconds =  16.54 MB/sec

/dev/hdd:
 Timing cached reads:   494 MB in  2.01 seconds = 246.32 MB/sec
 Timing buffered disk reads:   74 MB in  3.00 seconds =  24.64 MB/sec

Looks to me, my hda and hdb are way slower für cached reads only, while hdc
and hdd are way slower on both tests.

Can someone please explain me, what these tests mean and what I could
possibly do.

Regards,
  Steffen

Attachment: smime.p7s
Description: S/MIME cryptographic signature

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users