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7.1. Optimization Factor

Optimization of DRX is accomplished by adjusting the DRX internal parameters or by changing the settings of the system so that the buffering and compression functions provided by DRX can achieve optimal performance. The performance of DRX can be buffered up to 6 to 7 Gbps in a 10 Gbps network, and it can be said that the performance is adequate when the compression is 1.5 times more than that. However, these high-performance processing results ​​are based on the assumption that the DRX transmission network bandwidth of the TX side is sufficient, and usually can not show such throughput in the WAN interval. Therefore, in the case of such a high level I/O load state, It is difficult to optimize the performance of DRX in situations where random high level I/O load occurs in such a low transmission band, and it is necessary to check the bandwidth situation of WAN section in advance through proper level simulation for I/O load. DRX provides the drbdsim tool to perform these checks.

In general, the network bandwidth can be checked with tools such as iperf, and iperf calculates the maximum bandwidth the network can make. drbdsim injects I/O load into DRX from local drbdsim and receives remote relayed data from remote drbdsim to calculate the throughput that DRX can process on the network. Therefore, DRX will perform best when iperf's result is equal to drbdsim's or when drbdsim's is greater than it by compression. Please refer to Appendix F. drbdsim usage guide for more information on how to use drbdsim.

Based on the above, the factors of optimization are summarized as follows:

  • Replication I/O load
  • Network Bandwidth
  • DRX Buffering
  • Compression


Latency and throughput optimization on the local I/O side should be handled with optimization on the replication side. For this, please refer to the following.


7.2. Performance Indicator

Performance for the DRX can be viewed through the CLI commands provided by the DRX.

7.2.1 BAB Performance : memusage

This command checks the usage rate and latency of the BAB.

  • Check the performance of BAB through BAB usage and latency.

    • You can check the usage rate of the BAB set by calculation of "2. Operating Environment".

    • You can see where bottlenecks have occurred by increasing or decreasing the latency value.

  • Output Sample

    • Capacity : Indicates the BAB size set in the resource, in Kilobytes.
    • Use (Size) : Indicates BAB usage rate and Size. The unit of size is Kilobytes.
    • BAB Latency is the current (cur), average (avg), maximum (max), and minimum (min) values ​​for the TX, RX, Compress, and Decompress items. The unit is microseconds.
      memusage 
      < general output >
[root@c73-p1 dgkim]# drx-ctl mem all
--------------------------------------------------------------------------------------
Name                 Capacity Use (Size)                                  Full Counts 
--------------------------------------------------------------------------------------
DR-1-3-c73-p2-c73-p1 716800   [>>>>>>>.....................] 23% (163277) 0           
                     10240    [............................]  0% (0)      -           
--------------------------------------------------------------------------------------
DR-2-3-c73-p2-c73-p1 512000   [............................]  0% (0)      0           
                     10240    [............................]  0% (0)      -           
--------------------------------------------------------------------------------------
 Active bab counts : 2

< verbose output >
[root@c73-p1 dgkim]# drx-ctl mem all -v
----------------------------------------------------------------------------------------------------------
Name                 Capacity Begin     End       Use (Size)                                  Full Counts 
----------------------------------------------------------------------------------------------------------
DR-1-3-c73-p2-c73-p1 716800   340236152 504137496 [>>>>>>>.....................] 22% (160060) 0           
                     10240    0         0         [............................]  0% (0)      -           
----------------------------------------------------------------------------------------------------------
DR-2-3-c73-p2-c73-p1 512000   64273922  64273922  [............................]  0% (0)      0           
                     10240    0         0         [............................]  0% (0)      -           
----------------------------------------------------------------------------------------------------------
 Active bab counts : 2
----------------------------------------------------------------------------------------------------------
name                 Latency    cur             avg             max             min             
----------------------------------------------------------------------------------------------------------
DR-1-3-c73-p2-c73-p1 TX BAB     00:00:00.000000 00:00:00.443516 00:00:06.765142 00:00:00.000101 
                     RX BAB     00:00:00.000000 00:00:00.000000 00:00:00.000000 00:00:00.000000 
                     Compress   00:00:00.000088 00:00:00.000087 00:00:00.001439 00:00:00.000001 
                     Decompress 00:00:00.000000 00:00:00.000000 00:00:00.000000 00:00:00.000000 
----------------------------------------------------------------------------------------------------------
DR-2-3-c73-p2-c73-p1 TX BAB     00:00:00.000000 00:00:00.001627 00:00:00.004173 00:00:00.000261 
                     RX BAB     00:00:00.000000 00:00:00.000000 00:00:00.000000 00:00:00.000000 
                     Compress   00:00:00.000000 00:00:00.000113 00:00:00.001440 00:00:00.000001 
                     Decompress 00:00:00.000000 00:00:00.000000 00:00:00.000000 00:00:00.000000 
----------------------------------------------------------------------------------------------------------
 Active bab counts : 2
[root@c73-p1 dgkim]#

7.2.2 Compression performance statistics.: statistics

This command checks the DRX statistics information.

  • To view compression statistics, use the filter option in Output mode. 
    • The compression ratio represents the average value and the compression efficiency of the data to be transmitted can be checked.
    • Compression plug-in performance can be checked by the average compression time (cp-avg) and the decompression average time (dc-avg).

  • Sample command.

    drx-ctl st all -v --filter=name,type,ratio,cur,best,worst,cp-avg,cp-cur,cp-min,cp-max,dc-avg,dc-cur,dc-min,dc-max
  • Output Sample
    • The unit of size is Kilobytes.

    • 압축 ratio는 (압축전 사이즈 / 압축후 사이즈)로 계산되기 때문에 가독성을 위해서 소수점 둘째 자리까지 출력됩니다. 

    • The unit of compress(cp), decompress(de), encypto(ec), decrypto(dc) is microseconds.
      statistics 
      < verbose output >
[root@c69-1 drbd.d]# drx-ctl st all -v
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
name           type tx  rx t-raw t-net r-raw r-net ratio cur  best  worst cp-avg   cp-cur cp-min   cp-max   ec-avg ec-cur ec-min ec-max dc-avg dc-cur dc-min dc-max de-avg   de-cur de-min   de-max   
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
r0-c69-2-c69-1 data 184 0  13660 6821  0     1     1.93  0.00 18.07 1.00  0.000098 0      0.000001 0.013818 0      0      0      0      0      0      0      0      0.000189 0      0.000001 0.002338 
r0-c69-2-c69-1 meta 0   0  
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 All connections : 2, Established : 2
[root@c69-1 drbd.d]#


< use the filter option output>
[root@c69-1 drbd.d]# drx-ctl st all -v --filter=name,type,ratio,cur,best,worst,cp-avg,cp-cur,cp-min,cp-max,dc-avg,dc-cur,dc-min,dc-max
-----------------------------------------------------------------------------------------------------------
name           type ratio cur  best  worst cp-avg   cp-cur   cp-min   cp-max   dc-avg dc-cur dc-min dc-max 
-----------------------------------------------------------------------------------------------------------
r0-c69-2-c69-1 data 1.91  1.94 18.07 1.00  0.000088 0.000139 0.000001 0.013818 0      0      0      0      
r0-c69-2-c69-1 meta 
-----------------------------------------------------------------------------------------------------------
 All connections : 2, Established : 2
[root@c69-1 drbd.d]#
    • 축약어 설명
      축약어설명축약어설명축약어설명
      txTX speedratiocompress average ratioecencrypto
      rxRX speedcurcompress current ratio dcdecrypto
      t-netTX-Network 전송 사이즈worstcompress worst ratio

      t-rawTX RAW 사이즈bestcompress best ratio

      r-rawRX-Network 전송 사이즈cpcompress

      r-netRX RAW 사이즈dedecompress

7.3. Optimization procedure

7.3.1 Adjust the buffer size

7.3.2 Adjusting the number of compressing threads

7.4. Others

For DRX Appliance, you can perform optimizations on the local replication I/O reception intervals that work with DRBD. DRX is primarily designed to perform buffering in the application address space, so performance may vary depending on the receiving performance of the OS kernel of the appliance, which is directly linked to DRBD. Therefore, you can tune the receive buffer of this OS kernel socket to further enhance RX receive performance. To ensure that the OS kernel has enough receive buffers, it is necessary to apply the following to the OS kernel.








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