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alexanderfotiFlag for United Kingdom of Great Britain and Northern Ireland

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Debian Drive transfer speed on VMware ESX

Hi all

I have an unusual problem with Disk transfer speeds on a virtual Linux environment.

This environment consists of an ESX host running 3i, 3.5.0, 153875 and 2 Debian 5.0 Linux virtual machines.

When booting the machines have a hdparm transfer rate output of:

 /dev/sda:
 Timing cached reads:   1418 MB in  2.00 seconds = 707.95 MB/sec
 Timing buffered disk reads:  132 MB in  3.01 seconds =  43.93 MB/sec

After a couple of days, the machines become sluggish and the same test produces:

/dev/sda:
 Timing cached reads:   162 MB in  2.00 seconds =  80.99 MB/sec
 Timing buffered disk reads:   12 MB in  3.78 seconds =   3.18 MB/sec


The command that is being run is hdparm -tT /dev/sda

Any ideas on why this is occurring, I cant see anything obvious in the logs that will cause this.
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bgoering
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Is your vm configured with IDE drives?
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ASKER

No its an ESX server, you are only able to choose SCSI Devices.
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bgoering
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Many Thanks.

I have turned off VSMP on both boxes and have restarted them. Now all we have to do is wait until they slow down again now!

I have also removed more than one core from the virtual machines, so at the moment, they only have 1 core each.
Sounds good - keep us posted
Bad news - HDparm results today:

/dev/sda:
 Timing cached reads:   1394 MB in  2.00 seconds = 695.98 MB/sec
 Timing buffered disk reads:    8 MB in  3.81 seconds =   2.10 MB/sec

Any ideas?
After restarting the host, it appears the drive speeds have now returned to normal. Many thanksk