HP-UX System Administrator's Guide: Routine Management Tasks

NOTE: For a JFS file system, you can use mkfs -m to see the parameters the file
system was created with. But adjusting the client’s read/write buffer size to match
is probably not worthwhile because the configured block size does not govern all
of the blocks. See “Examining File System Characteristics” (page 153).
• On the NFS client, use HP SMH to check read/write block size.
Go to Tools, Disks and File Systems, File Systems and select each imported
file system in turn to view read and write buffer sizes. Refer to the Detailed View
at the bottom of the page under Mount Options.
Read Buffer Size and Write Buffer Size should match the file system’s
block size on the server.
If it does not, you can use HP SMH to change it.
Modify NFS Server/Client Block Size
1. Access the HP SMH Homepage as root.
2. Select Tools, Disks and File Systems, File Systems.
3. Unmount the file system by clicking on the Unmount/Remove... action on the
right side of the page.
4. Check the Unmount box and click on the Unmount/Remove button at the bottom
of the page. The file system will be unmounted.
5. Click on the Done button to return to the File Systems page.
6. Your file system should still be selected. Click on the ModifyNFS... action on the
right side of the page. This will display the Modify NFS File System page.
7. Enter the desired Read and Write buffer sizes, select Mount now and save
configuration in /etc/fstab , and click on the Modify NFS button.
8. Click on the Done button. You will be returned to the File Systems page. The selected
file system will be remounted with the new buffer sizes
Checking for Asynchronous Writes
Enabling asynchronous writes tells the NFS server to send the client an immediate
acknowledgment of a write request, before writing the data to disk. This improves NFS
throughput, allowing the client to post a second write request while the server is still
writing out the first.
This involves some risk to data integrity, but in most cases the performance
improvement is worth the risk.
You can use HP SMH to see whether asynchronous writes are enabled on a server’s
shared file systems.
1. Access the HP SMH Homepage as root.
Measuring Performance 195