Posted by boa on 08/21/06 15:32

* Robert Klemme wrote, On 21.08.2006 16:14:
> 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).
>

My mistake, I missed the *general* part of your remark. Sorry about
that. Yes, we're definitely OLTP for "the rest" of the db traffic so I
totally agree with you there.

Boa

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