Re: sqlserver 2005: indexes on raid-0?

* Robert Klemme wrote, On 21.08.2006 14:01:
On 21.08.2006 14:26, boa sema wrote:


[snip]



I see these issues with your theory:

- Disks with cache on them will optimize accesses to minimize latency created by head moves.

- With a RAID since disk != physical disk there is not a single head that moves and read and write requests are scheduled by the RAID controller to optimize IO operations.

I agree that these issues are real, OTOH isn't "my theory" also the reason one places the transaction logs on separate drives? If not, what's the difference?

Access patterns are completely different for data files and TX log. In an OLTP environment TX log is continuously written and you need a RAID level that supports fast writing and high reliability. Data files are read and written with arbitrary (although optimized) access patterns.

I meant during import. I haven't read the sql server algorithm for page and extent allocation when inserting new rows in a table, but assuming that sql server will start adding rows at page 0,extent 0 (also assuming proper clustering of table data and the order of the data inserted) and then just go from there, the access pattern should be pretty similar, shouldn't it?

Boa

[snip]
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