On 31/03/2008, Scott Long <scottl_at_samsco.org> wrote: > For writes, the performance penalty of smaller I/O's (assuming no RAID-5 > effects) is minimal; most caching controllers and drives will batch the > concurrent requests together, so the only loss is in the slight overhead > of the extra transaction setup and completion. For reads, the penalty > can be greater because the controller/disk will try to execute the first > request immediately and not wait for the second part to be requested, > leading to the potential for extra rotational and head movement delays. > Many caching RAID controllers offer a read-ahead feature to counteract > this. However, while my testing has shown little measurable benefit to > this, YMMV. Thank you, this is the kind of explanation I hoping for. One more thing: is TCQ (e.g. the SCSI variant) orthogonal to this?Received on Mon Mar 31 2008 - 19:34:09 UTC
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