Thanks for your replies and pointers, Johann and Zach. I hope to find
time next week to study the extra information.
Kind regards,
Herta
Zach Brown wrote:
Herta Van den Eynde wrote:
Given that the default journaling mode of ext3 (i.e. ordered), does not
guarantee write ordering after a crash, is this journaling mode safe
enough to use for a database such as Oracle?
Yes, the database doesn't rely the kind of functionality that
data=journaled provides that data=ordered doesn't. data=ordered is fine.
If so, how are out of sync writes delt with?
The database, just like ext3/jbd, implements its own consistency
mechanisms by careful write ordering. ext3 uses in-kernel device APIs
to issue writes and find out when they're on disk, the database ideally
uses O_DIRECT.
I looked around otn.oracle.com to find a doc that talks about
configuring and verifying AIO+O_DIRECT in the database but got tired of
searching. You might be able to find something if you're more patient
than I was.
- z
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