Posted by Robert Klemme on 08/21/06 15:14

On 21.08.2006 16:43, boa wrote:
> * Robert Klemme wrote, On 21.08.2006 14:01:
>>> 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?

Note that I made a *general* remark about OLTP systems. Yours seems to
be at least partly OLTP (the non insert stuff).

robert

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