134 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning
the characteristics of data on your DS6000 and without using a capacity planning tool like
Disk Magic. Refer to 4.1, “Disk Magic” on page 86.
We recommend that you monitor the read hit ratio over an extended period of time:
If the cache hit ratio has been low historically, it is most likely due to the nature of your
data, and you do not have much control over this. You can first try to perform
de-fragmentation on a file system, making indexes if none exist, rather than considering
increasing the cache size.
If you have a high cache hit ratio initially, and it is decreasing as you load more data with
the same characteristics, then moving some data to another cluster that ...