[lustre-discuss] Correct use of "lctl get_param health_check"

[Thomas Roth]

Hi Dominic,

it us a useful  parameter to include in some monitoring/alerting.
We've had unhealthy OSTs from overloading the servers, for example. Ideally, your monitoring would alert you _before_ an OST becomes unhealthy, but if 
not, at least then you have to intervene. (Although Lustre goes on, of course - can go on even with an unhealthy MDT ... until your users start 
protesting).

If a server does not have Lustre mounted, there is nothing there that could be unhealthy - therefore you shouldn't get a health warning then.

Of course, you need another monitoring to check if all your wanted targets are actually mounted.

Cheers
Thomas

On 6/11/26 3:21 PM, Dominic Sloan-Murphy via lustre-discuss wrote:
> Hi all,
> 
> Would you be able to advise on the correct use of the "lctl get_param health_check" command from https://wiki.lustre.org/Lustre_Health_Checks 
> <https://wiki.lustre.org/Lustre_Health_Checks> and under which circumstances it reports errors?
> 
> I've found it always returns "healthy", even when I intentionally break my test setup. For example, removing Lustre mounts:
> 
> root at lustre-build:~# mount -t lustre mytestpool/mgsmdt /mnt/mgs_mdt
> root at lustre-build:~# mount -t lustre ostpool/ost1 /mnt/ost
> root at lustre-build:~# lctl get_param health_check
> health_check=healthy
> root at lustre-build:~# umount /mnt/ost
> root at lustre-build:~# lctl get_param health_check
> health_check=healthy
> root at lustre-build:~# umount /mnt/mgs_mdt
> root at lustre-build:~# lctl get_param health_check
> health_check=healthy
> 
> My setup is a single Ubuntu 24.04 VM with Lustre 2.17 built from source. The Lustre file system was created with:
> 
> root at lustre-build:~# truncate -s 5G /root/mgs_mdt.img
> root at lustre-build:~# truncate -s 10G /root/ost.img
> root at lustre-build:~# mkfs.lustre --mgs --mdt --backfstype=zfs --fsname=mytestfs --index=0 mytestpool/mgsmdt /root/mgs_mdt.img
> root at lustre-build:~# MGS_IP=$(hostname -I | awk '{print $1}')
> root at lustre-build:~# mkfs.lustre --ost --backfstype=zfs --fsname=mytestfs --mgsnode=${MGS_IP}@tcp0 --index=0 ostpool/ost1 /root/ost.img
> 
> Regards,
> Dominic
> 
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Thomas Roth
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