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RGS3
Enthusiast
Enthusiast

1024kb blocks and higher result in SUPER bad performance

All my VM's are getting very bad performance running Disk Bench at 1024KB blocks and beyond

What could cause this? Below is a snapshot of a SQL server which has been performing pretty poorly lately.

Storage is iSCSI StoneFly SAN. These benchmarks used to be very consistent.

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ephillipsme
Enthusiast
Enthusiast

Is the disk and file system blocks aligned? This may help http://www.vmware.com/vmtn/resources/608

~Ernie

VCP3,VCP4, MCSE, CCA

~Ernie
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RGS3
Enthusiast
Enthusiast

I have just realized that this is just happening on one particular ESX host...very strange

Any ideas?

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LucasAlbers
Expert
Expert

compare the cluster size for your raid volume between the poorly and decently performing hosts.

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RGS3
Enthusiast
Enthusiast

I don't think it would be the storage raid block size since it happens to the same VMs but when I Vmotion them off to another ESX host they're fine. When I vmotion back, they'r effed again.

I'm thinking bad cabling or something particular to that ESX host. Bad NIC maybe?? Whats weird is that it happens over both paths to the storage (I have 2 nics and multipathing setup for iSCSI) I disable one NIC and and run the test and its bad...I disable the other run again and still bad.

Will do some more digging when I get to work tomorrow.

Any other suggestions? What else could it possibly be?

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