Using Solstice DiskSuite or Online: DiskSuite to Spread Disk Access Load

A common problem in NFS servers is poor load balancing across disk drives and disk controllers.

To balance loads, do the following:

• Balance loads by physical usage instead of logical usage. Use Solstice DiskSuite or Online: DiskSuite to spread disk access across disk drives transparently by using its striping and mirroring functions.

The disk mirroring feature of Solstice DiskSuite or Online: DiskSuite improves disk access time and reduces disk usage by providing access to two or three copies of the same data. This is particularly true in environments dominated by read operations. Write operations are normally slower on a mirrored disk since two or three writes must be accomplished for each logical operation requested.

• Balance loads using disk concatenation when disks are relatively full. This procedure accomplishes a minimum amount of load balancing

• If your environment is data-intensive, stripe the disk with a small interlace to improve disk throughput and distribute the service load. Disk striping improves read and write performance for serial applications. Use 64 Kbytes per number of disks in the stripe as a starting point for interlace size.

• If your environment is attribute-intensive, where random access dominates disk usage, stripe the disk with the default interlace (one disk cylinder).

• Use the iostat and sar commands to report disk drive usage.

Attaining even disk usage usually requires some iterations of monitoring and data reorganization. In addition, usage patterns change over time. A data layout that works when installed may perform poorly a year later. For more information on checking disk drive usage, see "Checking the NFS Server" in Chapter 3, Analyzing NFS Performance.