Data Domain: EVT-QUOTA-00001: Mtree Quota Soft limit reached

Users logged into a DD may see alerts such as "Mtree Quota Soft limit reached", for example:

sysadmin@dd02# alerts show current Id Post Time Severity Class Object Message ---- ------------------------ -------- ---------- --------------------------- ------------------------------------------------ m0-3 Tue Aug 13 18:45:03 2019 WARNING Filesystem Mtree=/data/col1/quota_test EVT-QUOTA-00001: Mtree Quota Soft limit reached. ---- ------------------------ -------- ---------- --------------------------- ------------------------------------------------ There is 1 active alert.

The cause for this alert is that soft quota is assigned to an MTree in the DD and the amount of data (pre-comp) in such MTree has exceeded the configured soft limit. Quotas are a useful way to manage growth for data in separate MTrees, with the "soft limit" just raising an alert the amount of pre-comp data in the MTree has exceeded the threshold, so the backup administrator has advance notice and sufficient time to see if growth is as expected in case there are some corrective actions needed.

To show the configured quota values for an MTree, use a command like the following:

sysadmin@dd# quota capacity show mtrees /data/col1/quota_test Mtree Pre-Comp (MiB) Soft-Limit (MiB) Hard-Limit (MiB) --------------------- -------------- ---------------- ---------------- /data/col1/quota_test 6 2 2048 --------------------- -------------- ---------------- ----------------

Note quotas control the amount of original backup data (pre-comp) stored under a particular MTree. The DD has no support for setting quotas on disk space used by backups (post-comp), so by using quotas you are not setting the maximum amount of disk space any MTree may use, but the maximum amount of backups that may be in a given MTree, which depending on relative compression values for data, may not be correlated to disk space really used.

To see a good estimate of how much disk space data in particular MTrees is using, please refer to Data Domain Operating System (DDOS) physical capacity measurement/reporting (PCM/PCR) frequently asked questions

When the soft limit is reached, an alert will be generated, however operations on the MTree (such as new backups being written to it) will continue as normal. If the customer wants to remove this alert three are three options as follows:


Option 1: Increase the soft quota limit for the mtree marked in the alert. Continuing with the example above, after checking the amount of backups in the MTree is as expected, you may raise the soft limit to a higher value, for example:

# quota capacity set mtrees /data/col1/quota_test soft-limit 100 MiB

Option 2 : it may be that you don't really want to set a cap on the amount of backups in an MTree (for example, because you are interested in disk space used, but quotas work on pre-comp instead). In that case you can completely remove the soft quota from that MTree, while still keeping the "hard quota" in place:

# quota capacity reset mtrees /data/col1/quota_test soft-limit

If you want to get rid of both quota setting for the MTree, use instead:

# quota capacity reset mtrees /data/col1/quota_test

Option 3: if after analyzing the data in the MTree you determine there are more backups than expected, expire some backup files from backup application. As quotas apply on pre-comp, the alert will go away as soon as the backup application has expired and deleted sufficient backups from the DD. Of course, disk space used by deleted backups will not be reclaimed from the DD until DD clean has been run and completed.


Below KB article will be further helpful to set quota via GUI instead of using the CLI if you prefer a graphical tool: How to Create and Modify Quotas within a Data Domain System