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 drxsim 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. drxsim injects I/O load into DRX from local drxsim and receives remote relayed data from remote drxsim to calculate the throughput that DRX can process on the network. Therefore, DRX will perform best when iperf's result is equal to drxsim's or when drxsim's is greater than it by compression. Please refer to drxsim usage guide for more information on how to use it.

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

• Replication I/O load

• Network Bandwidth

• DRX Buffering

• Compression

Performance Indicator

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

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 "2.4. Physical Memory Specifications".

  • 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]#

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.

  • The compression ratio is calculated as (original size / compressed size), so it is round down to 2 decimal places for readability.

  • The unit of compress(cp), decompress(de), encypto(ec), decrypto(dc) is microseconds.

    statistics

    < verbose output > [root@c69-1 bsr.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 bsr.d]# < use the filter option output> [root@c69-1 bsr.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 bsr.d]#

  • Abbreviations

Optimization procedure

DRX can optimize by adjusting the buffer size and compression options.

Buffer size

Size of the buffer is set via "memlimit" value in "proxy" section of the bsr configuration file.

Compression type and level

DRX provides the following compression plug-ins.

The command to set the compression plug-in is as follows.

Number of compressing threads

It is possible to change the number of threads processing packets.

The number of threads is set to "process-thread-count" value in the configuration file. If you do not set it or input "-1", it will operate at half the number of CPU cores.

• Commands

  process-thread-count

  < Configuration > [root@c73-1 bsr.d]# drx-ctl set process-thread-count 10 Result: done. [root@c73-1 bsr.d]# < Check > [root@c73-1 bsr.d]# drx-ctl show all ... ip-verification=on process-thread-count=10 [root@c73-1 bsr.d]#

Others

For DRX Appliance, you can perform optimizations on the local replication I/O reception intervals that work with bsr. 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 bsr. 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.

Linux Kernel Network Parameter

• Change TCP socket buffer size

  • Server used for testing : Server of Appliance Configuration Guide - eng - deprecated

  • References link : https://www.ibm.com/support/knowledgecenter/en/SSZTET_10.1/smpi01/smpi01_tysfbpjp.html

  • Default : 208KBytes

     

    [root@c73-1 bsr.d]# sysctl -a | grep net.core.[rw]mem net.core.rmem_default = 212992 net.core.rmem_max = 212992 net.core.wmem_default = 212992 net.core.wmem_max = 212992 [root@c73-1 bsr.d]#

  • Modify command : Change the max entry to 2 MBytes.

    sysctl -w net.core.rmem_max="2097152" sysctl -w net.core.wmem_max="2097152"