bptm process - causing performance bottleneck
Noticed performance drop when single bptm process spawn multiple duplication jobs.
Problem Description:
ServerA is backed up using "_Test_XYZ1Day" SLP. As per the SLP config, the backup goes to disk staging pool (Advance disk pool XYZStagingpool1) and then duplicated (3copies) to tape. Throughput of the duplication job to tape drive drops directly in proportion to the number of duplication per SLP. (NOTE: each duplication job uses a seperate Tape drive)
Test Results
- SLP _Test_XYZ1Day: Set with 1x Duplication job. Job uses 1 Tape drive and runs at throughput of 120 – 140MB/s. 120MB/sec sustained throughput most of the time.
- SLP _Test_XYZ1Day: Set with 2x Duplication job. Jobs will use 2 Tape drives and each of the jobs run at throughput of 80 – 85MB/s. 83MB/sec sustained throughput per drive most of the time.
- SLP _Test_XYZ1Day: Set with 3x Duplication job. Jobs will use 3 Tape drives and each of the jobs run at throughput of 53 – 58MB/s. 54MB/sec sustained throughput per drive most of the time.
NOTE: Combined throughtput of all the duplication jobs seems limited to 160 - 170MB/sec.
Test Conditions: All the above tests are stats are under below conditions
- Dedicated Staging Array used as a Advance Disk Pool.( 270+ MB/sec Sustained read throughtput )
- No other writes/read on the Array.
- To the same Tape library. (Stk SL500 with 5 LTO4 Drives)
- Single port dual HBA's connected to two different fabrics at 2gbit speeds. (3 tape drives on 1 fabric and 2 and controller on other)
Storage lifecycle policy details:
#nbstl _Test_XYZ1Day -L
Name: _Test_XYZ1Day
Data Classification: (none specified)
Duplication job priority: 0
State: active
Version: 5
Destination 1 Use for: backup
Storage Unit: XYZStagingPool1
Volume Pool: (none specified)
Server Group: (none specified)
Retention Type: Capacity Managed
Retention Level: 10 (1 day)
Alternate Read Server: (none specified)
Preserve Multiplexing: false
State: active
Source: (client)
Destination ID: (none specified)
Destination 2 Use for: duplication
Storage Unit: media3-hcart-tld-2
Volume Pool: temp_cp_test1
Server Group: Any
Retention Type: Fixed
Retention Level: 10 (1 day)
Alternate Read Server: (none specified)
Preserve Multiplexing: false
State: active
Source: (primary)
Destination ID: (none specified)
Destination 3 Use for: duplication
Storage Unit: media3-hcart-tld-2
Volume Pool: temp_cp_test1
Server Group: Any
Retention Type: Fixed
Retention Level: 10 (1 day)
Alternate Read Server: (none specified)
Preserve Multiplexing: false
State: active
Source: (primary)
Destination ID: (none specified)
Destination 4 Use for: duplication
Storage Unit: media3-hcart-tld-2
Volume Pool: temp_cp_test2
Server Group: Any
Retention Type: Fixed
Retention Level: 10 (1 day)
Alternate Read Server: (none specified)
Preserve Multiplexing: false
State: active
Source: (primary)
Destination ID: (none specified)
Any ideas would be appreciated.
Thanks.
Fully with you and your setup and tuning tests now.
The issue here is that you use inline copy and its handling of the bptm process which is a know problem.
This tech note explains it better http://www.symantec.com/docs/HOWTO56160
It maybe that you can think about this to see if there is a bottleneck anywhere that could help imporve things but the issue stems from using inline copy
Hope this helps