qmail alert: cannot start: unable to open mutex

For some reason the mail log was showing lots of:

Sep 23 09:40:03 hostname qmail: 1253695203.637058 alert: cannot start: unable to open mutex
Sep 23 10:32:16 hostname qmail: 1253698336.515510 alert: cannot start: unable to open mutex
Sep 23 10:32:21 hostname qmail: 1253698341.425333 alert: cannot start: unable to open mutex

and qmail was not working properly.

It turns out that for some reason /var/qmail/queue/lock/ was missing along with the file /var/qmail/queue/lock/sendmutex.  Had to recreate these with:

[root@hostname ~]# mkdir /var/qmail/queue/lock/
[root@hostname ~]# chown qmailq:qmail /var/qmail/queue/lock/
[root@hostname ~]# touch /var/qmail/queue/lock/sendmutex
[root@hostname ~]# chown qmails:qmail /var/qmail/queue/lock/sendmutex

Then qmail would start fine.


Restore incremental backup with Acronis

From this URL: Mounting an Image in Linux through Command Line

I couldn’t find this document when I needed it last time…


How to mount a full, differential or incremental backup archive through command line in Linux

These instructions apply to:

    • Acronis True Image 9.1 Server for Linux
    • Acronis True Image Echo Server for Linux
      1. Detect the index of a partition or a volume that you are going to mount:

        trueimagecmd –list –filename:/path/to/archive.tib

      2. Then mount the image:

        trueimagemnt –mount /mount/point –filename /path/to/archive.tib –index N

      1. Let us first create one full and two incremental archives of partitions sda1 and sdb1:

        trueimagecmd –list


        trueimagecmd –create –partition:1-1,2-1 –filename:/root/example.tib –progress:on


        trueimagecmd –create –partition:1-1,2-1 –filename:/root/example.tib –progress:on –incremental


        trueimagecmd –create –partition:1-1,2-1 –filename:/root/example.tib –progress:on –incremental


        Now we can see that there are three backup archives created:

        ls /root/example* -l


      2. Let us now mount the partition sda1.First of all we need to detect its index:

        trueimagecmd –list –filename:/root/example.tib


        Here the required index is 12. The index is 12 because we did not specify the option ?index for trueimagecmd and it accessed the last archive.

        Now we need to mount it:

        trueimagemnt –mount /mnt/example –filename /root/example.tib –index 12

      3. Now let us unmount it:

        trueimagemnt –umount /mnt/example


        This message is just a warning, not error. The system needs some time to free all resources before unmounting.

      4. Now let us mount the full archive.We need to use –index:1 for trueimagecmd in this case to find out its actual index:

        trueimagecmd –list –filename:/root/example.tib –index:1


        To mount sda1 we need to use 2 now as the actual index for trueimagemnt:

        trueimagemnt –mount /mnt/example –filename /root/example.tib –index 2

      • For trueimagecmd the –index option refers to the number of the backup archive: 0 means the latest backup archive, 1 means full backup archive, 2 means first incremental or differential backup archive, 3 means second incremental backup archive etc.
      • For trueimagemnt the –index option refers to the actual index of the backup archive. You need to specify this index to mount the archive.

To mount an image in Linux through command line, you need to do the following:

(!) Using a wrong index (non-existing or wrong partition type) will produce an error:


(!) –index option is different for trueimagecmd and trueimagemnt:

When issuing truemagecmd without the –index option, you will get the actual index of the last incremental backup archive.

For example, if you have several incremental archives and need to know the actual index of a partition in the third incremental archive, then the command will be:

trueimagecmd –list –index:4 –filename:/root/example.tib


(!)If there is a space gap in the name of the archive or in the name of the folder where the archive is, then any operation with the archive through command line will fail.

See trueimagecmd and trueimagemnt man-pages for more information.

The use of the –index option to restore an image is the same.