Re: Disk Failure Scenarios

["Michael Artz" <mlartz@xxxxxxxxx>]

> -Disk 2: If the transaction log dies, all changes since the last
> checkpoint are lost, right?  Again, if I set up an empty pg_xlog
> directory somewhere else, the DB should run just fine, right?

No, because there's no way to know what state the data pages are in.
Data may have made it to disk, may not have, partial page write, etc...

As far as I understand it, data is only written to the WAL except when the WAL is checkpointing, right?  So if your WAL disk crashes and you aren't int the middle of a checkpoint, there is a chance that you would just lose data since the last checkpoint.  Am I missing something?

Now the real question is: why are you trying to run without raid?

I have a single, very fast disk lying around, and I was
just wondering what parts of the DB I could "safely" put on it.  I
was thinking either the WAL or and index.  I have essentially 15
10K drives and 1 15K drive, and don't quite know what to do with it.

-Mike