Kris and Marty have great points. Also each workload is different, you
may or may not get sufficient benefit from it, depending upon your
access pattern and hit ratio (which Kris mentioned).
Regarding RECORDMDC, you may want to check the old VSE performance
papers by Wolfgang Kraemer, I seem to recall there may have been some
resolution to this issue at some point in the past.
On 02/17/2010 09:56 AM, Kris Buelens wrote:
MDC works at storage speed; controller cache needs to get out the z.
Ages ago (but still a bit valid to see gross orders)
Disk = 30 msec
CU Cache= 3 msec
Storage = xx nsec
An MDC cache hit is also less costly in CPU than a real IO. But, MDC
with a very poor hitratio makes you consume too much CPU.
Extra advantage MDC: when the wanted data are not in the MDC, CP reads
the whole track. Good for sequential processing. bad for random
access. Then you might want to look at using RECORDMDC instead (but,
I thinks that's only for CMS formatted minidisks, no help for VSE).
--
Rich Smrcina
Phone: 414-491-6001
http://www.linkedin.com/in/richsmrcina
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WAVV 2010 - Apr 9-13, 2010 Covington, KY
