Misleading data may be reported for device-mapper block devices

[nixsum]

The minor number of dm devices may change after system reboot if they initialize in a different order or simply after a device is removed, for example a logical volume. This will cause the "-p" flag to print wrong information.

For example, here I've generated load on logical volume "rl-a", it's minor number is 3

03:50:21 PM rl-a 77.23 0.08 150092.47 1943.42 5.02 64.96 4.96 38.35
03:50:21 PM rl-b 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
03:50:21 PM rl-c 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
03:50:21 PM rl-d 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

After I delete the rl-a logical volume and reboot the system sar will falsely report that rl-b was under load as it will take minor number 3

03:50:21 PM rl-b 77.23 0.08 150092.47 1943.42 5.02 64.96 4.96 38.35
03:50:21 PM rl-c 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
03:50:21 PM rl-d 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0

I have had this happen before without having to delete volumes, just a reboot was enough to change the order, but I'm unable to reproduce it.

sysstat version here is 11.7.3

[sysstat]

Try to use option -j to display persistent device names with sar.
Version 12.1.7 added stable identifier support for disks statistics. This stable identifier won't change across reboots for the same physical device. If it exists, this identifier is normally the WWN (World Wide Name) of the device, as read from the /dev/disk/by-id directory:

$ sar -d -j SID

08:10:30          tps     rkB/s     wkB/s     dkB/s   areq-sz    aqu-sz     await     %util DEV
08:15:30         5.61    186.75     11.27      0.00     35.30      0.01      0.96      0.38 0x538f6016100c3ec7
(...)