Re: Raid 5 on Sun arrays

mike > The default interlace size is 16k, which the manual says > "This is a reasonable value for most applications.". i have an SA as well, and ran into the same thing. i ran some tests of my own to figure out what was the best setting. what i found is that there is a difference, but it is not as much as i thought. still it is obviously best to optimize. i ran tests both on a striped volume and on raid-5 volumes, and came up with 16k as the best size for both. the tests that i ran were: a) load 1 million rows into a table b) update statistics medium c) create an index on one column d) do a null join of the table e) do a null index scan f) do a null sequential scan all these were null as i wasn't concerned with what it took to pass any data back, just in what it took to do the actual operations on the database. i ran it with sizes 8k, 40k, 64k and 16k. 16k was the overall winner in all cases, although there were a few where some tests were very close. as i said though, 16k was a clear overall winner. i wasn't all that concerned with load times, but did it just to see. it isn't that often that we are loading large amounts of data, and raid-5 is obviously slower on writes, unless you have a big, well managed cache. i forget how big the cache is on the SA. > Does anyone have a recommendation (or strong feeelings) for > what an appropriate size should be for database usage? The > server will be handling alot of batch processing in a logged > database. it depends what kind of batch processing you are going to be doing. if it involves a lot of loads and writes, or a lot of scans and some updates, etc... my best load time was with a stripe size of 40k, but all the other tests were slower than 16k. the difference in the load times here was ~3%. nothing phenominal. let me know if you have any qestions. mickm