#106 diskio module: only relies on physical block devices, not working with LUKS encrypted devices

[MobileHero]

The diskio module should optionally support monitoring device-mapper (dm-crypt) devices and follow through to underlying physical devices for I/O stats.

WebminStats diskio module currently only reads counters from /proc/diskstats for physical block devices/partitions.

It ignores mapper/virtual devices which results in “no new value” when they are used as monitored identifiers.

It also is unable to use any other reference mechanism next to the block device ("/dev/sdX"), like "/dev/disk/by-id/..." for example which would be quite dynamic.

Relying on physical block devices which are managed by the kernel and can change (and are changing) from time to time, making diskio module configuration a maintenance task or break the graphs if you don't think about this - and therefore rendering the module closely to useless, is a no-go in 2026.

[MobileHero]

Was not logged in yet (SF is so damn old... would be really great to have Webminstats on GitHub too!)... feel free to delete https://sourceforge.net/p/webminstats/bugs/105/.

[eric gerbier]

I have released a new version of diskio module (1.8) on https://sourceforge.net/projects/webminstats/files/updates/2.23/ which includes device mapper devices

[MobileHero]

Hmm... "nice"... right after upating to v1.8, all data seem to have been purged. Lost 365 days of diskio data.

Not even sure how to configure it, but the loss of historic data was... unexpected und unnecessary.

Update: restored the config.old. Graphs are generally back. Still not fully functional yet:
Now plenty of "ERROR while updating XX.rrd database : opening 'XX.rrd': No such file or directory" errors. Renaming XX.rrd.sav to XX.rrd solves this for some, but for others the files simply don't exist.

Update 2: everything back and running.

1️⃣ Can you now please elaborate on how to use device mapper devices to take advantage of a more dynamic configuration?
2️⃣ Same question regarding usage of "/dev/disk/by-id/..." --> is this possible now?

Thanks!

[eric gerbier]

Strange, the data should be kept on update. Could you send the log file (probably /var/webmin/modules/sysstats/webminstats.debug) and some infomations on your host (linux distribution,and version), webmin version ...