Hello everybody.
I would like to present an issue with a backup file filling out all available space. I’m talking about a RB1100 (powerpc) with RouterOS 6.44.3.

After many years launching a weekly backup, it began to have a huge size. Normally the backup file would be 1700 KB (1.7 MB) in size every week, but since last week it starts to grow until using all available disk space.

Before launching the backup, I have plenty of available disk space:
free-hdd-space: 476.1MiB
total-hdd-space: 512.0MiB

The command used to launch the backup is:
/system backup save dont-encrypt=yes name=SM-Router-2019-06-26

After running for a minute or so, the message received is:
Saving system configuration
Failed to save system configuration backup
action timed out - try again, if error continues contact MikroTik support and send a supout file (13)

After obtaining the error message, the file CONTINUES TO GROW until it uses all available disk space, resulting in a backup file of 472 MB!

The disk content is:
# NAME TYPE SIZE CREATION-TIME
0 SM-Router-2019-06-26.b... backup 472.6MiB jun/26/2019 09:46:21
1 SM-Router-2019-05-29.b... backup 1756.2KiB may/29/2019 08:00:02
2 SM-Router-2019-06-26.rsc script 218.3KiB jun/26/2019 09:37:46
3 SM-Router-2019-06-12.b... backup 1705.8KiB jun/12/2019 08:00:04
4 SM-Router-2019-06-12.rsc script 218.3KiB jun/12/2019 08:05:08
5 SM-Router-2019-06-05.b... backup 1686.5KiB jun/05/2019 08:00:02
6 SM-Router-2019-06-05.rsc script 218.3KiB jun/05/2019 08:05:04
7 SM-Router-2019-05-29.rsc script 218.3KiB may/29/2019 08:05:04
8 ZQU8-L5MZ.key .key file 204 jan/01/1970 21:46:06
9 skins directory jan/01/1970 21:47:31
10 pub directory oct/22/2012 11:36:01

The first file is the culprit of the lack of disk space. The resulting disk status is:
free-hdd-space: 2700.0KiB
total-hdd-space: 512.0MiB

As it is not possible to watch the contents of the binary backup file, I cannot know what is causing this huge size. The configuration of the router has not changed lately.

Along with the backup I always issue an export file, which works without any problem. I can obtain the rsc file but not the backup file. The command to get the rsc file is:
/export compact file=SM-Router-2019-06-26

What should I check?
Has anyone encountered this issue before?
Any thoughts?

Thank you in advance

Did you already follow the suggestion to make and send a supout file?
Did you try to reboot to see if that changes anything?

Did you already follow the suggestion to make and send a supout file?
Did you try to reboot to see if that changes anything?

Hello! Tjhank you for your reply.

Absolutely, I've sent the supout file and the support people told me the problem was my disk was full. I made the mistake of generating the supout file before deleting the extraordinarily big file created by the backup. The disk was full because of the misbehaving backup.

I have also restarted the device and tried to create the backup with the same result: it keeps filling all available disk space.

When you don't have too much stuff that is not contained in an export (users, groups, certificates etc) I would advise to
do a /export file=.... and download the file (but keep it on the router too), then make a connection via MAC and reset
the router (no defaults) and import the export file.
That should get rid of everything that is in the router but is not visible in the configuration interface.
Of course this means some downtime. Also make sure you have some experience in doing such things, e.g. practice on
a small router or CHR, as there are some pitfalls you do not want to run into while your network is down.

Thank you for your reply.
I like the solution you proposed. I'll have to plan it carefully because of the downtime associated.
I've been working with MikroTik routers since 2007 and it's the first time a backup behaves this way.
Thanks again.