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Article: 100008270
Last Published: 2022-07-05
Ratings: 0 0
Product(s): InfoScale & Storage Foundation
Problem
How to slow down plex resync or other VERITAS Volume Manager copy operationsSolution
The speeds of a plex resync and other VERITAS Volume Manager (VxVM) copy operations like vxrelayout are governed by two parameters: iosize and slow.
The optional parameter iosize defines the size of data blocks to be copied [default=32k]. Theoretically, the greater the block size the faster the copy process. For large values of iosize it can have a detrimental effect on other processes doing I/O.
The optional parameter 'slow' defines the number of milliseconds the copy process will pause until the next data block of size iosize gets processed[default=0].
The most effective way to lower the resync speed is to set the optional slow parameter: slow=iodelay
CaseA: lower the resync speed of a running process:
1. Check throttle setting [parameter slow]:
# vxtask -l list
Task: 179 RUNNING (Parent:178)
Type: ATCOPY
Operation: PLXATT Vol opt Plexopt-02
Started: Tue Mar 12 16:20:342002
Throttle: 0
Progress: 5.84% 612560 of 10487232Blocks
Work time: 38 seconds (10:12 remaining)
#
2. Increase the throttle setting:
# vxtask set slow=50 179
# vxtask -l list 179
Task: 179 RUNNING (Parent:178)
Type: ATCOPY
Operation: PLXATT Vol opt Plexopt-02
Started: Tue Mar 12 16:20:342002
Throttle: 50
Progress: 36.20% 3796880 of 10487232Blocks
Work time: 3 minutes, 46 seconds (44:38remaining)
#
Case B: start a new VxVM copy process with a lowered resync speed:
e.g: vxrecover -o slow=50 -sb
vxplex -g <DG> -o slow=30 att opt opt-02
vxassist -g <DG> -o slow=10 mirror opt
Check the new throttle setting [parameter slow] with vxtask -l list.
The optional parameter slow is accepted for a wide range of commands:
vxvol, vxplex, vxrelayout, vxassist,vxrecover.
If the resync speed of a process was reduced by too much it can always be set to a more appropriate level using the vxtask command as shown in case A.
The optional parameter iosize defines the size of data blocks to be copied [default=32k]. Theoretically, the greater the block size the faster the copy process. For large values of iosize it can have a detrimental effect on other processes doing I/O.
The optional parameter 'slow' defines the number of milliseconds the copy process will pause until the next data block of size iosize gets processed[default=0].
The most effective way to lower the resync speed is to set the optional slow parameter: slow=iodelay
CaseA: lower the resync speed of a running process:
1. Check throttle setting [parameter slow]:
# vxtask -l list
Task: 179 RUNNING (Parent:178)
Type: ATCOPY
Operation: PLXATT Vol opt Plexopt-02
Started: Tue Mar 12 16:20:342002
Throttle: 0
Progress: 5.84% 612560 of 10487232Blocks
Work time: 38 seconds (10:12 remaining)
#
2. Increase the throttle setting:
# vxtask set slow=50 179
# vxtask -l list 179
Task: 179 RUNNING (Parent:178)
Type: ATCOPY
Operation: PLXATT Vol opt Plexopt-02
Started: Tue Mar 12 16:20:342002
Throttle: 50
Progress: 36.20% 3796880 of 10487232Blocks
Work time: 3 minutes, 46 seconds (44:38remaining)
#
Case B: start a new VxVM copy process with a lowered resync speed:
e.g: vxrecover -o slow=50 -sb
vxplex -g <DG> -o slow=30 att opt opt-02
vxassist -g <DG> -o slow=10 mirror opt
Check the new throttle setting [parameter slow] with vxtask -l list.
The optional parameter slow is accepted for a wide range of commands:
vxvol, vxplex, vxrelayout, vxassist,vxrecover.
If the resync speed of a process was reduced by too much it can always be set to a more appropriate level using the vxtask command as shown in case A.