Data Domain: Performance Tuning: Managing Data Streams

PURPOSE

This article describes how to verify whether the stream count on a Data Domain is too high, thus causing performance-related problems.

If too many streams are enabled, the Data Domain performance can become degraded to the point where data flow stops.

Conversely, if too few data streams are enabled, the Data Domain does not reach performance expectations.

• Data throughput is slow
• The Data Domain is not responding
• Poor performance

  APPLIES TO

• All Data Domain models
• All Software Releases

CAUSE

Performance can be degraded if more than the recommended number of data streams that the Data Domain can process are enabled.

Each backup file written to, or read from, a Data Domain is seen as a data stream.

SOLUTION

1. In the latest Auto Support (ASUP), look up the "SYSTEM SHOW PERFORMANCE LEGACY VIEW" section for the asset.

                     -----------Throughput (MB/s)----------- ---------------Protocol-----------------  Compression  ------Cache Miss--------  -----------Streams----------- -MTree Active-  -State-  -----Utilization-----  --Latency--  --------------------SS LOAD BALANCE(user/repl)---------------------   -----------------SS LOAD BALANCE(gc)-------------------- 
                                                                                                                                                                     Repl
Date       Time      Read  Write Repl Network  Repl Pre-comp ops/s  load      data(MB/s)    wait(ms/MB)  gcomp lcomp  thra unus ovhd data meta    rd/  wr/  r+/  w+/  in/ out      rd/wr      'CDPVMSFIRL'     CPU        disk       in ms      stream        prefetch      rd            wr            tot           prefetch       rd            wr            tot        
---------- --------  ----- ----- ----in/out--- ----in/out--- -----  --%--     --in/out---   --in/out---  ----- -----  ---- ---- ---- ---- ----  ----------------------------- --------------   -----------  --avg/max---- --max---  -avg/sdev-  ----------------------------avg/sdev-------------------------------   ----------------------------avg/sdev-------------------- 
2025/05/24 06:30:00    0.0   0.0   0.00/  0.00   0.00/  0.00     0 61117.08%  0.00/  0.00  27.60/ 34.00    0.0   0.0    0%   0%   0%   0%   0%    0/   0/   0/   0/   0/   0       0/ 0        -----------  2%/  7%[0]    7%[ 1]    7.4/ 33.3   133.0/  0.0   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B    0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B
2025/05/24 06:40:00    0.0   0.0   0.00/  0.00   0.00/  0.00     0 60708.55%  0.00/  0.00  25.43/ 31.10    0.0   0.0    0%   0%   0%   0%   0%    0/   0/   0/   0/   0/   0       0/ 0        -----------  2%/  7%[0]    7%[ 1]    5.4/ 22.2   133.0/  0.0   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B    0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B
2025/05/24 06:50:00    0.0   0.0   0.00/  0.00   0.00/  0.00     0 60913.23%  0.00/  0.00  25.00/ 33.67    0.0   0.0    0%   0%   0%   0%   0%    0/   0/   0/   0/   0/   0       0/ 0        -----------  2%/  6%[0]    5%[ 1]    4.7/ 17.8   133.0/  0.0   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B    0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B
2025/05/24 07:00:00    0.0   0.0   0.00/  0.00   0.00/  0.00     0 60709.10%  0.00/  0.00  23.80/ 31.32    0.0   0.0    0%   0%   0%   0%   0%    0/   0/   0/   0/   0/   0       0/ 0        -----------  2%/  6%[0]    5%[ 1]    5.0/ 18.6   133.0/  0.0   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B    0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B   0.0B/  0.0B

2. Check under the "Streams" section for rd (Read), wr (Write), and rw (Read-Write) stream counts.
   1. Verify that the cumulative count is not greater than the recommended value per Data Domain: Stream Counts Frequently Asked Questions (FAQ) (Log in as registered Dell Support user is required to view article.) See the Data Domain User Guide for your corresponding release for this information.
   2. The stream count should not exceed the total recommended value for Read streams.
   3. For more information, check Backup application guide.

• Data Domain: Backups to Data Domain System Are Taking Too Long (Log in as registered Dell Support user is required to view article.)
• Data Domain: Copying or Restoring from the Data Domain System is Taking Too Long
• Data Domain: Data Domain Not Responding (Log in as registered Dell Support user is required to view article.)
• Data Domain: Analyzing Slow Replication Issues (Log in as registered Dell Support user is required to view article.)