W2K Dynamic disk errors on SAN

I was just doing some reading on this last week, and remembered something that might help , (or not):

From the Windows Clustering chapter of Technet:

"Disk configuration
You cannot configure cluster storage devices as dynamic disks or spanned volumes (volume sets) if they will be used as cluster resources.
Disks to be used for cluster storage must be configured as basic disks and must be formatted using the NTFS file system. Windows 2000 does not support the use of dynamic disks or the features of dynamic disks, such as spanned volumes (volume sets), for cluster storage. You cannot change an existing cluster disk, such as the quorum disk, to a dynamic disk.
You cannot use the Encrypting File System, Remote Storage, or mountedvolumes on the cluster storage device.
"

Jordan

Solution:

This problem is related to the queue depth setting on the HBA. Hitachi storage ports can have up to 255 queues. Each lun assigned to the port uses X number of queues depending on the queue depth set. Our HBA's came with a default of 32.That means that you can only have 255/32=7.9 (7) Luns on that port. Since this server is in a SAN it is not efficient to have so few luns per HDS port.

By dropping the queue depth to 2 the problem is solved and there can be 127 luns per HDS port. More than that and Windows may experience DMIO's and lost hdisk.

Finally, higher queue depths will eat up processor bandwidth with little I/O perofmance gain. A queue depth of 2 is plenty for I/O performance.

Note - Dynamic disks and Basis disks are both subject to this, however, Dynamic disks are hyper sensitive.

Thanks!

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