Re: file system and raid performance

On Fri, 15 Aug 2008, Bruce Momjian wrote:

> 'data=writeback' is the recommended mount method for that file system, 
> though I see that is not mentioned in our official documentation.

While writeback has good performance characteristics, I don't know that 
I'd go so far as to support making that an official recommendation.  The 
integrity guarantees of that journaling mode are pretty weak.  Sure the 
database itself should be fine; it's got the WAL as a backup if the 
filesytem loses some recently written bits.  But I'd hate to see somebody 
switch to that mount option on this project's recommendation only to find 
some other files got corrupted on a power loss because of writeback's 
limited journalling.  ext3 has plenty of problem already without picking 
its least safe mode, and recommending writeback would need a carefully 
written warning to that effect.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD