I'm considering upgrading the storage system for some of my servers, and all the guides and manuals advise to consider the storage usage patterns of your app before deciding on a (RAID? SSD? iSCSI? NAS?) solution.
Is there a tool I can use which can tell me:
- if my servers are doing mostly sequential or random IO,
- if I'm doing more reads or more writes,
- the average read and write size,
- and whatever other info I can use to make a decision?
I know about iostat, and it seems I can use it to answer question 2. But I think I need other tools to answer the other questions.
It seems that people usually like to make educated guesses in these matters based on the running software, but I would much rather measure than reason.
The OS is ubuntu 8.04, but I'm willing to change the OS if something else has better measuring tools.