Vmware datastores on OceanStor 5500 V3 became failed and can‘t be mounted

Trouble Ticket Number

DTS2015091001112

Symptom

When random small read and write I/Os are sent to a 4K-sector disk, services are occasionally interrupted when the stripe depth of the storage pool is greater than or equal to 128 KB.

Severity

Suggestion.

Root Cause

If the stripe depth of the storage pool is greater than or equal to 128 KB, and the upper-layer services are random small I/Os, the upper-layer module integrates the size of I/Os sent to the 4K-sector disk into the I/Os whose size is no more than that of the stripe depth of the storage pool. When the number of memory pages of an integrated I/O occasionally exceeds the maximum of an I/O on the lower-layer module, the lower-layer module splits the integrated I/Os. The size of the split child I/Os may not be a multiple of the size of I/Os accepted by the 4K-sector disk; therefore, read and write I/O fail, resulting in occasional service interruption.

Solution

When the lower-layer module splits the I/Os that are sent to the 4K-sector disk, the module checks the size of each child I/O when it is split. If the size of the split I/Os is not a multiple of that of the I/Os accepted by the 4K-sector disk, the lower-layer module adjusts the size of the child I/Os to be a multiple of the I/Os accepted by the 4K-sector disk, and continues splitting the remaining I/Os.

Impact

There is no impact on the system.