On an EMC array is it possible to assign WRITE cache to wherever your transaction log files are?

Yes, provided that your transaction logs have their own LUN from the other files as the write cache is enabled and disabled at the LUN level.  By default read and write cache will be enabled for every LUN which is created on the array.

There aren’t to many cases where you would want to disable the write cache on a LUN except for maybe a data warehouse LUN where no data is updated, only new rows are written.  The reason for this is that these will be sequential writes, and the array will bypass the write cache when it detects that sequential writes are being done as these sequential writes can be done directly to disk about as quickly as they can be done to cache as once head gets into the correct place the writes are put done very quickly as the head and the spindle don’t need to move very far between each write operation.

Denny

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