Re: ORA-01575: timeout waiting for space management resource

On 6 Feb 1998, Catcox wrote:
>
> For some periods during the day I get a lot of the following message.
>
> ORA-01575: timeout waiting for space management resource
>
> During this time performance is very bad.

This means that smon timed out waiting on the ST (space management) enqueue. If you were to look at v$session_wait or v$session_event you would see that smon is spending a lot of time performing space management (adding extents, coalescing extents).

One way that you can avoid excessive ST queueing is by setting your temporary tablespace to type TEMPORARY (alter tablespace <tablespace> temporary;). That will allow oracle to reuse sort segments that have already been created, instead of recreating them every time someone seeds to sort to disk. Another place that a lot of ST stuff could be going on is in the rollback segments. If transactions keep having to grow rollback segments higher than their optimal size, and shrink them back down, these are space management transactions, and take time. If you have a slow I/O system, it increases the likelihood that you will encounter this problem.

--
Jeremiah Wilton      http://www.wolfenet.com/~jeremiah