vSphere Storage Appliance

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  • 1.  1024kb blocks and higher result in SUPER bad performance

    Posted Oct 24, 2009 11:07 PM

    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.



  • 2.  RE: 1024kb blocks and higher result in SUPER bad performance

    Posted Oct 25, 2009 12:37 AM

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

    ~Ernie

    VCP3,VCP4, MCSE, CCA



  • 3.  RE: 1024kb blocks and higher result in SUPER bad performance

    Posted Oct 25, 2009 02:02 AM

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

    Any ideas?



  • 4.  RE: 1024kb blocks and higher result in SUPER bad performance

    Posted Oct 25, 2009 11:38 PM

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



  • 5.  RE: 1024kb blocks and higher result in SUPER bad performance

    Posted Oct 26, 2009 01:45 AM

    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?