DMX-3 device write pending slots

Are you mainframe user ?
I¿m asking because you report some information abort ¿perma cache¿.
Where did you get this information from? From ECC Performance Monitor ?

Marcin

Cache size = 98304 Mb
Available cache: 2667626 * 32k / 1024 = 83363 Mb.
WP limit = 2136184 * 32k / 1024 = 66755 Mb.

WP limit is about 80% of available cache... That's what I expected it to be
Can you paste also details of other box ?? Maybe there is something else eating up cache .. however 80% sounds good to me

I think it's the output of a symcli command .. (I suspect it's from "symcfg")..

Permacache is simply a trade .. you buy more cache and you have a flash-drive without using real flash drives ..

With permacache, the code reserves as much cache as big is the volume you want to "speed up".

From a pure performance point of view Permacache is even better then flash drives since when you use permacache your data is ALWAYS in cache and you don't need to fetch blocks from the backend.

Message was edited by:
Stefano Del Corno

Solution Enabler have a nice variable you can enable in options file that enables a silent translation between 32K and 64K tracks .. If you have a DMX with 18414cyls devices and buy a DMX4, you ask your CE to build 9207 cyls devices (since our CE work directly on the storage) .. But if you use Solution Enabler to create devices on the DMX4 you still need to create 18414 cyls devices since S.E. will silently translate between 32K tracks (the ones you are supposed to use when you use symcli) and 64K tracks (that's how the hardware is actually working).

So you still work with 32k ? I thought it's 64k nowadays ?

Did we answer your question ?? Do you think you need better/different answers ??

The device WP limit is calculated quite differently in DMX3 and DMX4 from all previous generations of Symmetrix. In DMX3/4 the device WP limit is simply 5% of total writable cache. In previous generations it was derived from a complicated formula based on the number of large logical volumes in the box, but usually ended up at a very small percentage of total cache.

Quincy56, welcome to the forums.