Bob Friesenhahn wrote:
On Thu, 21 Feb 2013, Sašo Kiselkov wrote:
On 02/21/2013 12:27 AM, Peter Wood wrote:
Will adding another vdev hurt the performance?
In general, the answer is: no. ZFS will try to balance writes to
top-level vdevs in a fashion that assures even data distribution. If
your data is equally likely to be hit in all places, then you will not
incur any performance penalties. If, OTOH, newer data is more likely to
be hit than old data
, then yes, newer data will be served from fewer spindles. In that case
it is possible to do a send/receive of the affected datasets into new
locations and then renaming them.
You have this reversed. The older data is served from fewer spindles
than data written after the new vdev is added. Performance with the
newer data should be improved.
Not if the pool is close to full, when new data will end up on fewer
spindles (the new or extended vdev).
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