Guido . . .

Yes, SAS GRID works wonderfully with the Veritas Clustered File System. The following are best practices when running with Veritas File System and Veritas Volume manager

1. Use 8KB block size when creating a VxFS file system
2. Use multipathing.
3. When creating a Veritas volume use a RAID-0 stripe across multiple LUNs (assuming LUNS are RAID protected).
4. Depending upon the underlying LUN characteristics make the VxVM strip size be equal to a full stripe-width on the underlying LUN. For example if a LUN is a RAID-5 volume created as a 4+1 with a 64KB strip size, the strip size for the host should be 256KB.
5. In the above case the SAS BUFSIZE parameter should be set to 256KB in the SAS configuration file.
6. If SAS BUFSIZE is 256KB or larger use vxtunefs to increase the value of discovery_direct_iosz.
7. If SAS BUFSIZE is 256KB or less change the vxtunefs parameters
• Read_perf_io
• Write_perf_io
to match the SAS BUFSIZE otherwise make the values an integer divisor of the SAS BUFSIZE.
8. Check read_nstream and write_nstream values are set appropriately from VxVM volume configuration.
9. Mount the SASWORK temporary file system(s) with tmplog and mincache=tmpcache.

In SAS Version 9.1 and 9.2 have users modify LIBNAME statement to add offset=value, where value is the SAS BUFSIZE. Using the example above (5) add offset=256K to the LIBNAME statement. In version 9.3 put –alignsasiofiles in the V9 config file.

By default a SAS data set contains 512 bytes of header data. The actual SAS data begins in the file at an 8K offset and the file is written to with BUFSIZE IO request sizes. When offset= is set then the first data page will be at “offset” in the file.

Margaret