Kbase P60270: Clients occasionally pause for short periods of time when connected to a very large active database,
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
23/02/2010 |
|
Status: Verified
SYMPTOM(s):
Clients occasionally pause for short periods of time when connected to a very large active database, caused by UNIX sync, fixed by using -directio
UNIX sync command causes a pause at time of checkpoint.
FACT(s) (Environment):
UNIX
Progress 9.x
CAUSE:
At the time of triggering a bi checkpoint the bi mechanism must go through all modified database blocks found in the full bi clusters and place them onto the checkpoint queue.
Also, after the checkpoint it will issue a UNIX SYNC to tell the operating system to flush all modified O/S blocks from the UNIX cache. All processes writing to the O/S must wait until this has completed.
With very active databases often with large bi cluster sizes, this task can take a fair amount of time and could become quite noticeable to the clients.
FIX:
Use the database startup parameter -directio to spread the I/O load.
You should review Progress Solution 20688 as it contains important information and considerations when using -directio. It is possible that your database may perform worse with -directio enabled.