How to use device mapper (dmsetup) for delay read/write
I wanted to simulate slow disk (disk latency) on my ubuntu 14. I have come across https://www.mjmwired.net/kernel/Documentation/device-mapper/delay.txt documentation which highlights adding delay with the specified amount of time.
But, finding difficult to understand the usage of the command. Can some one please help me in understanding the below example quoted in Kernel documentation link pasted above?
[[
17 #!/bin/sh
18 # Create device delaying rw operation for 500ms
19 echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
20 ]]
21
- Question1 : What is $1 in the above script?
- Question2 : Which all location/paths/mounts gets impacted with the above delay read and write command?
- Question3 : I want to delay read/write for /var/lib location. On my Ubuntu, /var is mounted as
/dev/mapper/vg-var on /var type ext4 (rw,errors=panic)
How may I modify the above script (dmsetup) to create delay read / write for /var/lib?
kernel mount performance disk io
asked 15 mins ago
DineshDinesh
103
add a comment |
I wanted to simulate slow disk (disk latency) on my ubuntu 14. I have come across https://www.mjmwired.net/kernel/Documentation/device-mapper/delay.txt documentation which highlights adding delay with the specified amount of time.
But, finding difficult to understand the usage of the command. Can some one please help me in understanding the below example quoted in Kernel documentation link pasted above?
[[
17 #!/bin/sh
18 # Create device delaying rw operation for 500ms
19 echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
20 ]]
21
- Question1 : What is $1 in the above script?
- Question2 : Which all location/paths/mounts gets impacted with the above delay read and write command?
- Question3 : I want to delay read/write for /var/lib location. On my Ubuntu, /var is mounted as
/dev/mapper/vg-var on /var type ext4 (rw,errors=panic)
How may I modify the above script (dmsetup) to create delay read / write for /var/lib?
kernel mount performance disk io
asked 15 mins ago
DineshDinesh
103
add a comment |
I wanted to simulate slow disk (disk latency) on my ubuntu 14. I have come across https://www.mjmwired.net/kernel/Documentation/device-mapper/delay.txt documentation which highlights adding delay with the specified amount of time.
But, finding difficult to understand the usage of the command. Can some one please help me in understanding the below example quoted in Kernel documentation link pasted above?
[[
17 #!/bin/sh
18 # Create device delaying rw operation for 500ms
19 echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
20 ]]
21
- Question1 : What is $1 in the above script?
- Question2 : Which all location/paths/mounts gets impacted with the above delay read and write command?
- Question3 : I want to delay read/write for /var/lib location. On my Ubuntu, /var is mounted as
/dev/mapper/vg-var on /var type ext4 (rw,errors=panic)
How may I modify the above script (dmsetup) to create delay read / write for /var/lib?
kernel mount performance disk io
asked 15 mins ago
DineshDinesh
103
I wanted to simulate slow disk (disk latency) on my ubuntu 14. I have come across https://www.mjmwired.net/kernel/Documentation/device-mapper/delay.txt documentation which highlights adding delay with the specified amount of time.
But, finding difficult to understand the usage of the command. Can some one please help me in understanding the below example quoted in Kernel documentation link pasted above?
[[
17 #!/bin/sh
18 # Create device delaying rw operation for 500ms
19 echo "0 `blockdev --getsz $1` delay $1 0 500" | dmsetup create delayed
20 ]]
21
- Question1 : What is $1 in the above script?
- Question2 : Which all location/paths/mounts gets impacted with the above delay read and write command?
- Question3 : I want to delay read/write for /var/lib location. On my Ubuntu, /var is mounted as
/dev/mapper/vg-var on /var type ext4 (rw,errors=panic)
How may I modify the above script (dmsetup) to create delay read / write for /var/lib?
kernel mount performance disk io
kernel mount performance disk io
asked 15 mins ago
DineshDinesh
103
asked 15 mins ago
DineshDinesh
103
asked 15 mins ago
DineshDinesh
103
asked 15 mins ago
DineshDinesh
103
asked 15 mins ago
DineshDinesh
103
103
add a comment |
add a comment |
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