dm critical when not available

[tesink]

Hi Glen,

Thanks for the great plugin. Since version 4.0.2 we have one issue; the plugin is issuing critical exit messages when there are no dm devices:

CRITICAL: dm:[No devices to check]: megacli:[Volumes(0): : Devices(4): 00,01,02,03=Online]

Please let me know if you need more details on this issue.

[glensc]

use 4.0.1 if you don't need dm monitoring, 4.0.2 only change was to add dm plugin.

to make it more flexible is planned in #138

[tersmitten]

Just upgraded to 4.0.3 now I'm having trouble with dm:[No devices to check]:

UNKNOWN: dm:[No devices to check]; hpacucli:[Smart Array P410[OK]: Array A(OK)[LUN1:OK]]

I found this --noraid=OK. Is that the (only) way to get thinks working again?

[glensc]

given you need just one plugin to check, -p hpacucli from the output

[tersmitten]

Ok, but why does it check dm by default?

[prupert]

IMHO it should only do dm checks if there actually are arrays configured in dm.

[glensc]

because this is by design. read README.md and related bugreports linked from this issue, feel free to help and send your version of PR.

[glensc]

@prupert read the related bugreports

[calestyo]

Is there a way to set --noraid=OK just for a specific plugin (i.e. dm)?
The thing is, most people will have dmsetup installed even if not using MD at all, simply because DM is much more than just RAID/MD (dm-crypt, dm-integrity, cache and so on).

OTOH, I'd like to avoid using -p, cause it seems nice that check_raid simply works out-of-the box on every node, when the respective raid tools are installed.

[glensc]

the specific case is that dm is not properly implemented, i believe link to #138 explains it. as you see no one has implemented anything since that. due lack of time, lack of interest or lack of knowledge.

i personally deploy this plugin from source and remove dm.pm :)

[calestyo]

Ah, I see =)

Maybe the following could be done:

# dmsetup status
system: 0 1965027328 crypt 

status gives a list of all DM devices and their type, with the types given in the manpage in the TABLE FORMAT section.

So check_raid could first run dmsetup status, and grep per default for types which are actually something like a RAID, e.g.:
mirror and raid

With and plugin option one could allow people to override which types they look for, including "", i.e. ignore anything.

Unless a device in the list remains after that matching, dm would simply be ignored in check_raid

[glensc]

technical implementation was discussed somewhere in tickets/pr's. if really interested try reading and navigating between them yourself (likely there are cross references). i recall top of my head that why the detect was not done was related to sudo invocation. haven't got time to deal with it any more.

[glensc]

started work on dm-detect branch:

however there's technical problem with sudo rules:

• current test to see if plugin should be enabled requires sudo access (because dmsetup status requires root)
• sudo rules are generated based whether plugin is enabled or not

so in the end plugin never be enabled for non-root because sudo rules are not generated.

so it's kind of chicken-egg problem. it needs to be solved first.

other solution would be to disable it by default, and require special option to enable the plugin. this would be easy to implement, but likely will break existing installations.