/dev/sdX (where X is a letter) is not a mount point (that must be a
directory). It is a device. It should contain some partition(s) /dev/sdXY
(where Y is a number). Such a partition can mounted wherever you want. For
instance, to mount the partition 1 of the disk b on /mnt:
$ sudo mount /dev/sdb1 /mnt
That said, suspension should not create such problems. Are we talking about
partitions mounted at init? If so, how are they identified in the first
column of /etc/fstab (by UUID, by label or the device node)?
Memtest86+ is not on Trisquel ISOs. That means you cannot test your memory
with the Trisquel live system (well, actually, you can with by install
"memtester" that does not require a reboot). You can install the "memtest86+"
package on Trisquel though.
