Re: I/O Wait for Datasets Sequentail File
Posted: Thu Jan 20, 2011 2:48 pm
When you run the "ls -l" command in the datasets directory, how many files are listed when the command returns?
Does the command hang if you run it in another directory?
High I/O waits are usually caused by one or more of:
1) Hardware contention (I/O channels, disk drives, network for NAS)
2) High number of files in a directory (thousands)
3) Too small of a block size/buffer size with high data volumes
Your description points me first towards the second option as you mention that ls -l also seems to hang. The number of files in a directory has a direct impact on how long it takes to access within the directory...the o/s must step through the directory listing in order to find the requested file information.
Also, have any new processes (DataStage or non-DataStage) been implemented on your servers? How about new source files or a sudden increase in data quantities?
Regards,
Does the command hang if you run it in another directory?
High I/O waits are usually caused by one or more of:
1) Hardware contention (I/O channels, disk drives, network for NAS)
2) High number of files in a directory (thousands)
3) Too small of a block size/buffer size with high data volumes
Your description points me first towards the second option as you mention that ls -l also seems to hang. The number of files in a directory has a direct impact on how long it takes to access within the directory...the o/s must step through the directory listing in order to find the requested file information.
Also, have any new processes (DataStage or non-DataStage) been implemented on your servers? How about new source files or a sudden increase in data quantities?
Regards,