Hello Bart,

Wednesday, May 16, 2007, 6:07:36 PM, you wrote:

BS> Bill Moloney wrote:
>> for example, doing sequential 1MB writes to a  
>> previously written) zvol (simple catenation of 5 
>> FC drives in a JBOD) and writing 2GB of data induced 
>> more than 4GB of IO to the drives (with smaller write 
>> sizes this ratio gets progressively worse)

BS> How did you measure this?  This would imply that rewriting
BS> a zvol would be limited at below 50% of disk bandwidth, not
BS> something I'm seeing at all.

Perhaps zvol was created with default 128k block size, then smaller
writes were issued. Perhaps lowering volblocksize to 8k or whatever
avarage (or constant?) io size he is using would help?

-- 
Best regards,
 Robert                            mailto:[EMAIL PROTECTED]
                                       http://milek.blogspot.com

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