I am currently questioning our AuxCopy to tape performance and want to get some input on how to identify the bottleneck.
We have multiple plans which all have two copies to tape. One is synchronous and one is selective.
Each of the two is consolidated onto another Global Secondary Copy Policy.
The storage target are six LTO9 drives with a mixed LTO8 and LTO9 media inventory.
The source for the copy is a NetApp StorageGRID S3 backed storage pool with deduplication connected on a 100G fiber network.
We have two Media Agents which are both connected to all LTO drives and the NetApp (same VLAN).
Looking at the reported speed of the drives in Commvault I get around 130MB/s all of the time.
I could confirm this looking at SFP speeds on the FC switch which also stay around this value with rare peaks to around 200MB/s.
What I tested already to look for the bottleneck:
- only run one AuxCopy Job
- run AuxCopy when no other jobs where running
- validate drive > 300MB/s throughput with LTO8 media
- different multiplexing settings: none, 5, 10, 20
- no Hardware compression
Total throughput with all drives is > 1GB/s but an individual drive always stays in the mentioned speed range.
All the testing in my opinion points to a bottleneck in the AuxCopy process itself.
Furthermore I wanted to look into the Performance Analysis Tool but unfortunately every job where I looked at the PerfAnalysis.log it was empty.
Is it really just a limitation of the software or could there be more to it?
I know this is a complex topic but maybe there are some settings I am missing out on here.
