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

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.

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

Abbreviation	Description	Abbreviation	Description	Abbreviation	Description
tx	TX speed	ratio	compress average ratio	ec	encrypto
rx	RX speed	cur	compress current ratio	dc	decrypto
t-net	TX network total relayed bytes	worst	compress worst ratio
t-raw	TX network total transferred bytes	best	compress best ratio
r-net	RX network total relayed bytes	cp	compress
r-raw	RX network total transferred bytes	de	decompress

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.

proxy {
	memlimit 1G;
}

Compression type and level

DRX provides the following compression plug-ins.

Type	System	Level range	Remarks
ZLIB	SW	1~9	-
LZ4	SW	1~9	-
NONE	-	-	OFF

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

Type	Commands	Example output
ZLIB	drx-ctl set compress zlib [level] [connect name]	set compress Expand source < Set compression plug-in to ZLIB > [root@c73-1 bsr.d]# drx-ctl set compress zlib 1 r0-c73-2-c73-1 r0-c73-2-c73-1: updated. Result: 1 resource(s) updated. [root@c73-1 bsr.d]#
LZ4	drx-ctl set compress lz4 [level] [connect name]	set compress Expand source < Set compression plug-in to LZ4 > [root@c73-1 bsr.d]# drx-ctl set compress lz4 1 r0-c73-2-c73-1 r0-c73-2-c73-1: updated. Result: 1 resource(s) updated. [root@c73-1 bsr.d]#
NONE	drx-ctl set compress none 0 [connect name]	set compress Expand source < Turn off compression plug-ins > [root@c73-1 bsr.d]# drx-ctl set compress none 0 r0-c73-2-c73-1 r0-c73-2-c73-1: updated. Result: 1 resource(s) updated. [root@c73-1 bsr.d]#

Type

Commands

Example output

ZLIB

drx-ctl set compress zlib [level] [connect name]

set compress

< Set compression plug-in to ZLIB >
[root@c73-1 bsr.d]# drx-ctl set compress zlib 1 r0-c73-2-c73-1
r0-c73-2-c73-1: updated.
Result: 1 resource(s) updated.

[root@c73-1 bsr.d]#

LZ4

drx-ctl set compress lz4 [level] [connect name]

set compress

< Set compression plug-in to LZ4 >
[root@c73-1 bsr.d]# drx-ctl set compress lz4 1 r0-c73-2-c73-1
r0-c73-2-c73-1: updated.
Result: 1 resource(s) updated.

[root@c73-1 bsr.d]#

NONE

drx-ctl set compress none 0 [connect name]

set compress

< Turn off compression plug-ins >
[root@c73-1 bsr.d]# drx-ctl set compress none 0 r0-c73-2-c73-1
r0-c73-2-c73-1: updated.
Result: 1 resource(s) updated.

[root@c73-1 bsr.d]#

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

Changing the value using sysctl should be aware that there is a risk that the system will crash.

If you set an unreasonable value to the system, it may stop immediately, so it should be done after enough testing.

Change TCP socket buffer size
- Server used for testing : Server of /wiki/spaces/PX/pages/901775481
- 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" 
```
  The set value is not an absolute value and the performance result may be different depending on server and network environment.

Browser not supported