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J1mbo
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Improve Disk Performance?

Hi!

Just wondering if there are any tweaks to get more out of SATA disk? Copying an ISO between two 2k3 guests (on the same machine but different drives) I'm averaging about 20MB/s.

NB Proliant ML115 G5, quad-core optron 1352.

Many thanks, James.

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kjb007
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That's fine. It's hard to gain more efficiencies with a single disk. You are limited to the spindle speed, and can only improve things by making sure disk cache is enabled, which it should be. A pass-through disk is different. In this case, you're close to a passthrough, but your vm does not have direct access to the disk, as it goes through ESX to get at those blocks. A passthrough disk is controlled completely by the VM, and is not available, yet.

-KjB

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vExpert/VCP/VCAP vmwise.com / @vmwise -KjB

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kjb007
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Are you using single disk datastores?

-KjB

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vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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J1mbo
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Hi, thanks for the reply.

Each data store consists of a single disk. I've created a .vmdk for each OS - I'm not sure if there is a disk pass-through mode? As this box has no hardware RAID I'm reluctant to add more than one drive but am very greatful for the input if this is misguided!

Many thanks.

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kjb007
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That's fine. It's hard to gain more efficiencies with a single disk. You are limited to the spindle speed, and can only improve things by making sure disk cache is enabled, which it should be. A pass-through disk is different. In this case, you're close to a passthrough, but your vm does not have direct access to the disk, as it goes through ESX to get at those blocks. A passthrough disk is controlled completely by the VM, and is not available, yet.

-KjB

VMware vExpert

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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J1mbo
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OK thanks for your help, much appreciated.

The disks themselves (WD RE2's) can do about 80MB/s natively, obviously the effect of the sheer overhead of the data travelling through four OS's and a virtual LAN switch all running through the same CPU.

Performance massively better than hyper-V on my test platform though Smiley Happy

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