That is: Is the Log writer laszy by default? E.g. does it wait until log pages are full to flush them to disk? Or is this a Win32 specifica where Windows plainly ignores requests for syncing file writes? How does SAP DB force a sync on Win32?
Perhaps SAPDB does a sync, and Windows flushes it's buffers. That might only mean, that the data is within the harddisk's cache-memory.
Hi,
this reminds me of a question I meant to ask some time ago:
In order to increase stability I use raw devices for all data and log devices, because the filesystem cache is not involved. As I understand, this does however reduce performance. Some OSs have async i/o built into their kernel which will improve performance on raw devices. On linux there is the KAIO patch available: http://oss.sgi.com/projects/kaio/
Question 1: Does SAP-DB support async i/o on raw devices?
Question 2: Does anybody know if the KAIO patches are included in the current linux kernel release??
Thanks, Arne
-- Institute of Shipping Economics and Logistics http://www.isl.org/ Arne Gehlhaar mailto:[EMAIL PROTECTED] Universitaetsallee GW1 Block A phone:+49.421.22096.49 D-28359 Bremen, Germany fax:+49.421.22096.55
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