the Error Information "Can not Write Image to Media" is Displayed

Publication Date:  2012-07-18 Views:  190 Downloads:  0
Issue Description
When you use the tape caching utility of the VTL3605, data on several tapes fails to be backed up with the error information "can not write image to media" displayed. Log in to the VTL3605 and find that these tapes are of direct line to tape and others are of auto tape cache.
Alarm Information
None
Handling Process
Change the trigger condition for space reclamation to No More Space, that is, space reclamation is triggered only when the VTL3605 has no available storage space. The storage space reclamation threshold is 90% by default. When the VTL3605 storage space utilization ratio reaches 90%, the virtual tape space starts being reclaimed.
Before the VTL3605 storage space utilization ratio reaches 90%, backup data is directly written onto virtual tapes and the VTL3605 serves as a backup cache, which efficiently improves system performance.
Root Cause
The tape caching utility is improperly configured. In Tape Caching Policy, Reclamation Triggers is wrongly set to Immediate.
The customer purchases the VTL3605 to improve backup performance, requiring that data start being backed up from the midnight and migrated from the VTL3605 to a physical tape library at 8:00 am.
After the data on virtual tapes is successfully migrated to the physical tape library on the first day, the virtual tapes become pointers. Then, the backup data is redirected to the physical tape library during each daily backup. In this way, the VTL3605 cannot exert its function as the backup cache and contributes noting to performance improvement.
Suggestions
In tape caching, backup data is directly written onto virtual tapes of the VTL3605 and then migrated to a physical tape library when Data Migration Triggers is enabled. After data migration is complete, the VTL3605 starts reclaiming virtual tape storage space when Reclamation Triggers is enabled. After storage space reclamation is complete, all virtual tapes with backup data become direct link. After that, all backups are redirected to physical tapes by the VTL3605 until physical tapes expire. When physical tapes expire, writing data to them by using backup software enables the VTL3605 to start Renew Cache, that is, allocating storage space to virtual tapes to which physical tapes correspond. As a result, virtual tapes becoming direct link can serve as the backup cache of physical tapes again and backup data can be directly written onto virtual tapes.
Change the trigger condition for space reclamation to No More Space.

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