22.0.0.SPC3
The following lists the issue resolved in the Kunpeng BoostKit 22.0.0.SPC3 SDS Global Cache 1.3.15 patch.
Trouble Ticket No. |
DTS2022122207239 |
|---|---|
Symptom |
The write performance in the non-full hit scenario with the block size being 128 or 256 KB is much lower than the expected performance (with a fluctuation rate greater than 10%), which does not meet the requirement. |
Severity |
Major |
Cause Analysis |
When the block size of wcache is 128 KB or 256 KB, write back is performed by default. The granularity of write data stored in wcache is 4 KB+64 bytes whereas the data flushing granularity is 4 KB. To reduce the number of I/Os, the persistence layer supplements the data flushing granularity to 8 KB, doubling the bandwidth. As a result, the current NVMe drive encounters a bandwidth bottleneck. |
Solution |
Change the write-through threshold to 128 KB. |
Impact |
The defect is rectified, and no other impact is imposed. |
Test Suggestion |
Reserve 3 TB storage space for Ceph and use 16 KB data blocks to perform 7:3 random read/write operations. |