Squashfs not enabled

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Sam

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Jun 17, 2021, 5:42:30 PMJun 17
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I am new to singularity. So bear with me.
I installed singularity 3.8.0 per the instructions on a Centos7 system.
Installation went fine. When I try to run the example "singularity run llcow_latest.sif" I get an error: squashfs filesystem seems not enabled and/or supported by your kernel.
I have the squashfs rpm's installed. However I don't see squashfs in /proc/filesystems.
What should I do?

David Trudgian

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Jun 17, 2021, 6:17:55 PMJun 17
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The squashfs filesystem won't necessarily be listed in /proc/filesystems but it is strange for it not to work on CentOS 7.

Are you running a custom or standard kernel? i.e. output of `uname -a`

Take a look at the output of the `dmesg` command for any error information from the kernel... it may show an error when it was asked by SingularityCE to mount the squashfs filesystem.

You can also run singularity with the `-d` flag to see if there is more information.

DT

Sam

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Jun 17, 2021, 7:47:29 PMJun 17
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The kernel is standard. No customizations. Pertinent parts of uname -a : Linux 3.10.0-1160.25.1.el7.x86_64 #1 SMP x86_64 GNU/Linux
Running with -d showed a lot of lines with nothing problematic except the last line:
FATAL Master() container creation failed: mount /proc/self/fd/3 -> /usr/local/var/singularity/mnt/session/rootfs error: while mounting image /proc/self/fd/3: squashfs filesystem seems not enabled and/or supported by your kernel
/proc/self/fd/3 -> /var/lib/sss/mc/passwd
ls -al /var/lib/sss/mc/passwd :  -rw-rw-r-- sssd:sssd 8825056
/usr/local/var/singularity/mnt/session existed. There was no subdirectory rootfs. So I created one. Still fails.
dmesg has no reference to squashfs.

Sam

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Jun 17, 2021, 8:04:33 PMJun 17
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I noticed one entry in the debug lines just before the FATAL line.
mountImage() Mounting loop device /dev/loop0 to /usr/local/var/singularity/mnt/session/rootfs of type squashfs

So it looks like there was already a mount completed on /usr/local/var/singularity/mnt/session/rootfs. And the next line is where it fails to mount /proc/self/fd/3 on the same mount point.

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