Re: New Linux xfs/reiser file systems

mlw wrote:

>Bruce Momjian wrote:
>
>>>Just put a note in the installation docs that the place where the database
>>>is initialised to should be on a non-Reiser, non-XFS mount...
>>>
>>Sure, we can do that now. What do we do when these are the default file
>>systems for Linux? We can tell them to create other types of file
>>systems, but that is a pretty big hurdle. I wonder if it would be
>>easier to get reiser/xfs to make some modifications.
>>
>
>
>I have looked at Reiser, and I don't think it is a file system suited for very
>large files, or applications such as postgres. The Linux crowd should lobby
>against any such trend. It is ok for many moderately small files. ReiserFS
>would be great for a cddb server, but poor for a database box.
>
>XFS is a real big file system project, I'd bet that there are file properties
>or management tools to tell it to leave directories and files alone. They
>should have addressed that years ago.
>
>One last mention..
>
>Having better control over WHERE various files in a database are located can
>make it easier to deal with these things.
>
I think it's worth noting that Oracle has been petitioning the kernel
developers for better raw device support: in other words, the ability to
write directly to the hard disk and bypassing the filesystem all
together.

If the db is going to assume the responsibility of disk write
verification it seems reasonable to assume you might want to investigate
the raw disk i/o options.

Telling your installers that a major performance gain is attainable by
doing so might be a start in the opposite direction. I've monitored a
lot of discussions and from what I can gather, postgresql does it's own
set of journaling operations. I don't think that it's necessary for
writes to be double journalled anyway.

Again, just my two cents worth...