HP Integrity NonStop J-Series - Manual (Page 43)

Preparing to Use SMF
HP NonStop Storage Management Foundation User's Guide—523562-007
2-9
Placing Existing Volumes in Storage Pools
Placing Existing Volumes in Storage Pools
It is possible to place existing physical disks in storage pools. The files on these disks
will still be accessible to non-SMF processes. However, virtual disk processes
associated with the pool will be able to place files managed by SMF on these disks as
well.
Converting to Virtual Volumes
SMF provides a conversion utility called SMCONVRT, which is used to change existing
direct volumes into virtual disks. Upon completion of such a conversion, SMCONVRT
renames the physical disk and creates a new virtual disk on the system with the
physical volume’s old name. All files may be referenced by using the same file names
as before, but these names are now location independent. The files are physically
located on the same device, but the physical files have been renamed to ZYS*.*.
In a few circumstances, files cannot be converted. For these cases, the SMCONVRT
utility reports these exceptions and permits you to decide whether the conversion is to
finish or the operation is to be backed out.
For more information on SMCONVRT (and the SMREVERT utility, used to convert
virtual disks back to direct volumes), see
Section 4, Migration Guidelines .
Volume Selection
Any application that performs volume selection should not operate as if two different
volume name components indicate two different physical devices (see
Parallelism and
Co-Location on page 2-5). Therefore, you should design any application that selects
volumes for space or performance purposes to use one of these two approaches to
volume selection:

SMF volume selection. If all files are created on the same virtual disk, the SMF
physical volume selection algorithm may be used to distribute the files among
volumes in a storage pool to best meet specific space and performance goals.
Multiple virtual disks could be used to spread volumes across more storage pools.

Direct files. The application could be modified to exclude subtype 36 (virtual) disk
processes when choosing volumes.
An application that has not been converted to run on the SMF subsystem may not
execute correctly with SMF, depending on the application’s method of selecting
volumes. Such applications may perform the tasks they were designed to perform but
may not deliver expected performance.
Temporary Files
Temporary files are files whose subvolume component name begins with a pound sign
(#). The disk process (DP2) treats temporary files differently than it treats permanent
files. In particular, the disk process purges temporary files when the last open is
closed. DP2 also automatically purges any existing temporary files when it is initialized.