2. USAGE GUIDELINES › 2.2 VTS Component Usage Guidelines › 2.2.2 Virtual Tape Performance Analysis › 2.2.2.2 STK VSM Virtual Tape Performance

2.2.2.2 STK VSM Virtual Tape Performance

 
StorageTek Virtual Storage Manager (VSM) stores the virtual
tape volumes (VTVs) on the disk buffer of the Virtual Tape
Storage Subsystem (VTSS).  Based on storage class
assignments, VSM may keep VTVs in the disk buffer to allow
for quick mount on recall, or migrate (stack) them onto
multivolume cartridges (MVCs).  VSM ensures that there is
sufficient space in the disk buffer to accommodate the demand
for VTV storage.
 
Refer to StorageTek documentation for specific measurement
thresholds that indicate performance degradation.  Key
performance considerations may include:
 
  o  Frequency of recall mounts
  o  Batch delay time incurred on recalls
  o  Premature migration and deletions from disk buffer
  o  I/O link saturation
  o  Disk buffer usage fluctuation
  o  Recalls within 24 hours of VTV creation
  o  Duration between creation and migration
 
Vendor-suggested guidelines can be compared to actual
performance using the VTS component files as follows:
 
o Subsystem Performance (SVTSSP) file
 
  - Disk buffer statistics
  - Percent free and used statistics
 
o Channel Interface Performance (SVTCIP) file
 
  - I/O link utilization
  - Link busy
  - Balanced I/O
 
o Virtual Tape Volume Mount Activity (SVTVMR) file
 
  - Batch delay time incurred on recalls
  - Disk buffer hit percentage
  - Disk buffer miss percentage
  - Frequency of recall mounts
  - Scratch tape mount time distribution
  - Specific tape mount time distribution
 
o Virtual Tape Volume Migrate Activity (SVTVGR) file
 
  - Duration between creation and migration
  - TOD migration management
 
o Virtual Tape Volume Recall Activity (SVTVRR) file
 
  - Recalls within 24 hours of creation
 
o Virtual Tape Volume Delete Activity (SVTVXR) file
 
  - Disk buffer VTV residency
 
o Real Tape Drive Mount Activity (SVTRMR) file
 
  - Real Tape drive mount performance
 
o Real Tape Drive Mount Activity (SVTRMR) file
 
  - Real Tape drive mount performance
 
o Real Tape Drive Performance (SVTRPR) file
s
 
  - Real Tape drive utilization
 
o StorageTek VTSS Summary (SVTSVS) file
 
  - Trending VTSS usage statistics