Oracle on an HP AutoRAID Model 12H, HP-UX 11i

[Betty Fessler]

And I just assigned points again and when I went back in they all disappeared again.

[Bob_Vance · Accepted solution]

The answer to your question is "no". You only have 45GB allocated to LUNs and have 50GB unallocated. Therefore, the 46GB will *always* all be in 1/0 (unless you start creating more LUNs :). Note, that, technically speaking, no space is actually taken up until you actually write some data. So, *theoretically*, you could have more than 50% of the space "allocated" to LUNs and still have all the data in 1/0, simply because not all has been written yet. Of course, this could be a temporary situation.

Also, just to be clear, the 10% limit is not based on the "theory that 90% of the data is unchanged". It's merely to *make sure* that *at least* 10% of the data will be in 1/0. If your active write set is greater than 10% and have no unallocated space, then the array will be forced into updating in 5. The 10% is a minimum cushion so that the situation will never arise that all data is in 5.

Also, the idea of multiple LUNs is further based on the fact the there is an I/O queue in the kernel for each LUN. If you only have one LUN, then all I/O to the array will be forced sequentially thru the one queue. HP recommends at least 3 queues (3 LUNs). By having more than 1 queue, multiple I/Os can be sent to the array, allowing seek overlap (head movement in parallel). Having multiple paths (2 controllers) further allows data transfer overlap.

bv

[Betty Fessler]

Great info, thanks. Now how do I get the points to stick
do I submit after entering the
points?