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OceanStor 2600T V1 When customer creates LUN snapshot, after running a period of time the LUN snapshot is “disable”

Publication Date:  2015-12-10 Views:  132 Downloads:  0
Issue Description
The customer creates a resource pool on each controller A and B. The controller (A)’s resource pool capacity is 500G and the controller (B)’s resource pool capacity is 100G.

The customer creates a virtual snapshot (LUN_ID_9_Snapshot001) for a 500G LUN (LUN009), and creates a snapshot copy (the Snapshot_ID_24_Copy001_N_Drive) for it.

Customer makes source LUN (LUN009) and virtual snapshot copy (Snapshot_ID_24_Copy001_N_Drive) mapped to the host for running business. After a period of time, the virtual snapshot and snapshot copy become "disable"
Alarm Information

Alarm information as follows:

Handling Process
To meet the business requirement, we need expand the capacity of resource pool (B). Specification limits:the total capacity (pool A + pool B) can’t exceed 667GB, as following:

The current capacity of resource pool (A) is 500G, resource pool (B) is 100G. The total capacity will reach the maximum value of the standard, so it has not been able to effectively expand resource pool (B) through adding resource LUN into resource pool (B). To expand resource pool (B) and meet the requirement of the specifications, we need reconstruct resource pool (A) and (B). Delete the original LUN of resource pool (A/B), re-add one LUN (100G) to resource pool (A) and one LUN (500G) to resource pool (B). To adjust the capacity of resource pool (A) to 100G, resource pool (B) to 500G. Make the virtual snapshot and snapshot copy activated, and run business for a period of time.
Root Cause
The working controller of source LUN (LUN009) is controller (B), which means that the virtual snapshot and snapshot copy are using the resource pool (B), that is 100G:

While source LUN (LUN009) ‘s capacity is 500G, then use source LUN and snapshot copy to run business, there is any change in the data will consume the space of resource pool (B). The resource pool (B)’s capacity is only 100G, far less than the size of source LUN and snapshot copy. In the scene of large business pressure and large data change, it is easy to fill to the full of resource pool, which results in disable of virtual snapshots and snapshot copy.
According to log, it’s found that before reporting disable alert of virtual snapshot and snapshot copy, there is an alarm about the utilization of resource pool (B) reaching the threshold (HUAWEI store sets the utilization threshold of resource pool in 80% by default) :

It’s found that the alarm (the utilization of resource pool (B) reaching the threshold 80%) is reported in the 01:40:31 2015-04-17, after 3min the alarm (virtual snapshot disable) is reported in the 01:43:49 2015-04-17. According to log, it’s failed that controller (B) applied for the resource pool (B) space in the 01:43:48 2015-04-17.

Therefore it’s confirmed that disable of virtual snapshot and snapshot copy is due to the full of resource pool (B), which is caused by large business pressure, then the pool can’t provide service continually.
Solution
To adjust the capacity of resource pool, refer to "Handling Process"
Suggestions
This kind problem of virtual snapshot is generally related with the source LUN and the resource pool, which is priority to troubleshoot these key points. At the same time pay attention to the time point of the alarm, whether there are any alarms or events related with virtual snapshot, which will help us to reduce the scope of troubleshooting.

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