I am not new to linux, but I am new to the underlying guts of it, and I don't know anything about LVM or device-mapper. I'm trying to troubleshoot a livecd mounting its live-rw (dm-0) file system as read only during operation, and it's been frustrating to put it mildly.
I've discovered that dmsetup status will display some numbers - I think snapshot size, but I'm not sure:
[root@localhost ~]# dmsetup status live-osimg-min: 0 4194304 snapshot 1272/1272 16 live-rw: 0 4194304 snapshot 7568/1048576 40
I've found that the far right numbers, the "7568/1048576" seem to determine the length of time my livecd has to live before it gets mounted read-only and dies. These numbers always start at the same amount and tick up as more activity is performed on the file system - regardless of the root partition's size. Commands like "yum update" are particularly harsh on this number.
I can't find any documentation online that labels the fields and describes what they are - in classic linux fashion, they're just some floating integers on a black background with absolutely no explanation, as if to say "good luck!".
Does anyone know what these numbers represent, and how I can increase the "cap" from 1048576 to something much larger when building a CentOS 6.6 livecd?