Re: Tablespaces on a raid configuration

On Fri, Mar 30, 2012 at 7:53 AM, ktm@rice.edu <ktm@rice.edu> wrote:
> On Fri, Mar 30, 2012 at 02:45:36PM +0000, Campbell, Lance wrote:
>> PostgreSQL 9.0.x
>> When PostgreSQL  storage is using a relatively large raid  5 or 6 array is there any value in having your tables
distributedacross multiple tablespaces if those tablespaces will exists on the same raid array?  I understand the value
ifyou were to have the tablespaces on different raid arrays.  But what about on the same one? 
>>
>>
>> Thanks,
>>
>> Lance Campbell
>> Software Architect
>> Web Services at Public Affairs
>> 217-333-0382
>>
>
> I have seen previous discussions about using different filesystems versus
> a single filesystem and one advantage that multiple tablespaces have is
> that an fsync on one table/tablespace would not block or be blocked by
> an fsync on a different table/tablespace at the OS level.

Another advantage is that you can use a non-journaling FS for the WAL
(ext2) and a journaling FS for the data (ext4 etc.).  I was told that
there's no reason to use a journaling fs for the WAL since the WAL is
a journal.

Craig