UNSOLVED
cache question - mainframe
Hi,
As I remember in DMX-3 cache slot size was increased to 64K. When we use DMX for mixed environment (open system and mainframe), we can expect that about 8K was wasted (64K ¿ 56K mainframe TRACK).
What about pure mainframe environment ?
Is a slot still 64K or 56K ?
Another question. Why z/OS RMF report shows only 52GB even if I have installed 64 (128 mirrored cache) ?
Marcin
As I remember in DMX-3 cache slot size was increased to 64K. When we use DMX for mixed environment (open system and mainframe), we can expect that about 8K was wasted (64K ¿ 56K mainframe TRACK).
What about pure mainframe environment ?
Is a slot still 64K or 56K ?
Another question. Why z/OS RMF report shows only 52GB even if I have installed 64 (128 mirrored cache) ?
Marcin
526
0
Posted July 14th, 2008 05:00
You indeed waste 8kB per cache slot.
Hit rate is based upon your I/O request, so if you have an 80% hit rate, 80% of the requests you came from cache. Does it matter whether or not this cache wastes about 8kB ? I guess not526
0
Posted July 14th, 2008 05:00
So if slot size is 64K in mainframe environment we waste about 8K (mainframe track = 56K). Is it true ?
If yes, I have the last question. On ECC we can observe and collect date about cache utilization.
Question:
100% (for example hit rate) is calculated based on 64K or 56K ?
In other hand, if I have 80% hit rate ¿ it is 80% from 64K or 80% from 56K ?
MarkF4
39 Posts
526
0
Posted July 13th, 2008 16:00
Mark Foreman
Host Systems Moderator