SQL Server 2005: Wait Type - PAGEIOLATCH_SH

PAGEIOLATCH_SH: Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. PAGEIOLATCH_SH waits is very brief as they are only held on a page during IO operations.

You can also identify I/O bottlenecks by examining the latch waits. These latch waits account for the physical I/O waits when a page is accessed for reading or writing and the page is not available in the buffer pool. When the page is not found in the buffer pool, an asynchronous I/O is posted and then the status of the I/O is checked. If I/O has already completed, the worker proceeds normally. Otherwise, it waits on PAGEIOLATCH_EX or PAGEIOLATCH_SH, depending upon the type of request. The following DMV query can be used to find I/O latch wait statistics.

Select  wait_type, 
        waiting_tasks_count, 
        wait_time_ms
from    sys.dm_os_wait_stats  
where    wait_type like 'PAGEIOLATCH%'  
order by wait_type

More detail information on performance probblems in SQL Server 2005, please navigate to the following article.

Troubleshooting Performance Problems in SQL Server 2005
http://www.microsoft.com/technet/prodtechnol/sql/2005/tsprfprb.mspx