Expert Advice |
KS3_VTS_Pct_Copy_Throt_Warn |
Situation Description
Possible Causes
Suggested Actions
Situation Description Throttling of copy operations (copy throttle) might occur in a source TS7700 tape virtualization engine (TS7700). This type of throttling happens when the cache of the TS7700 is more than 95% full of data that needs to be copied to target TS7700 peers. These peers are located in a TS7700 Grid configuration.
Possible Causes Copy throttling does not occur during normal operations. Normally, the links between the TS7700 peers operate and have adequate bandwidth and connectivity. There is one scenario in which copy throttling can occur on the source TS7700. This scenario arises when target TS7700 peers are unavailable for a period of time. The lack of availability could be caused by a failure in the links between the TS7700s. Also, this problem could be caused by an extended failure or service action against a target TS7700. While the target TS7700 is unavailable, the data in the cache of the source TS7700 increases until it is full. The source TS7700 detects that the target is unavailable and removes the oldest data from the cache to prevent the cache from overflowing. (Note: At this point, the oldest data has already been copied to physical tape that is attached to the source TS7700.) When the target TS7700 returns to service, the source TS7700 enters Copy Throttling mode, until the amount of data in the cache to copy falls below the 95% point. The duration of copy throttling depends on the amount of transfer bandwidth between the source and target TS7700. Usually the duration is less than a few hours.
Suggested Actions If copy throttling occurs while all peers are available, check for a failure in the links between the TS7700s. Contact the service team of your company for assistance.
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