When I run the below command while setting up dm-cache on my CentOS system, I receive the error:

device-mapper: reload ioctl on cache1 failed: Device or resource busy
Command failed

Command is:

dmsetup create 'cache1' --table '0 195309568 cache /dev/sdb  /dev/sda  512 1 writethrough default 0'

Does anyone have idea about this error or have faced this error while setting up dm-cache?

My dmesg output is

[1907480.058991] device-mapper: table: 253:3: cache: Error opening metadata device
[1907480.058996] device-mapper: ioctl: error adding target to table

The cache target requires 3 devices, but you have only specified two. I believe the devices also must be dm devices, not a scsi disk.

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  • well the cache is the name of the cache and /dev/sdb(cache device ,ssd) and /dev/sda(my hardisk ,source device) .Am i missing something here? – arpit joshi Apr 19 '16 at 0:00
  • @asj177, according to Documentation/device-mapper/cache.txt in the linux kernel sources, the cache target takes <metadata dev> <cache dev> <origin dev>. – psusi Apr 19 '16 at 1:59

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