HP Integrity NonStop J-Series - Manual (Page 44)

Preparing to Use SMF
HP NonStop Storage Management Foundation User's Guide—523562-007
2-10
Physical Disk Information Requests
Temporary files are supported on virtual disks, just as they are supported for direct
volumes and for systems not under SMF control. Therefore, a file can be created on a
virtual disk with temporary file characteristics: that is, with a subvolume name preceded
by a pound sign (the name is generated by the VDP). After the logical temporary file
has been created, an application may refer to it by its logical name: for example,
$L.#0000049.
Using a logical temporary file has no different functional result than that of using a
direct temporary file on the same physical volume; however, the process by which it is
purged differs. The virtual disk process does not track opens and closes of logical files;
therefore, it cannot detect when the last close of a logical temporary file occurs. As a
result, the virtual disk’s catalog may contain information about a logical temporary file
that no longer exists (in the view of the disk process), for a short period of time
following the last close of the temporary file.
Physical Disk Information Requests
Several different system procedures retrieve information about physical devices. These
requests have little or no meaning for virtual disk processes; consequently, the values
that are returned from these procedures may not be accurate.
Disk Product Number Information
System procedures that retrieve physical disk product numbers, revision levels, and
serial numbers return spaces when information about a type 3, subtype 36 (virtual disk)
is requested.
Applications that cannot tolerate a response of all spaces must be modified to work
properly where SMF virtual disks are present.
Disk Capacity Information
System procedures that retrieve information about physical storage allocation return -1
(negative one) when the capacity for a virtual disk is requested. Also, these processes
return 0 (zero) for free space count requests, fragment count requests, and largest
fragment size requests.
Applications that request this information must be modified to tolerate these values in
responses where SMF virtual disks are present.
File and Volume Label Changes
Disk Process 2 support for SMF includes changes to the file label and volume label.
These new structures are available to customers through the source file DDISCL. Any
user application that makes use of the file label or disk label might need to be
recompiled or have other changes made.