I'm trying to figure out how LVM snapshots work so I can implement it on my fileserver but I'm having difficulty finding anything on google that explains how it works instead of how to use it for a base backup system.
From what I've read I think it works something like this:
- You have an LVM with a primary partition and lots and lots of unallocated freespace not it the partition
- Then you take a snapshot and mount it on a new Logical Volume. Snapshots are supposed to be changes so this first snapshot would be a whole copy, correct?
- Then, the next day you take another snapshot (this one's partition size doesn't have to be so big) and mount it.
- Somehow the LVM keeps track of the snapshots, and doesn't store unchanged bits on the primary volume.
- Then you decide that you have enough snapshots and get rid of the first one. I have no idea how this works or how that would affect the next snapshot.
Can someone correct me where I'm wrong. At best, I'm guessing, I can't find anything on google.
obu1:/home/jail/home/qps/backup/D# vgdisplay --- Volume group --- VG Name fileserverLVM System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 3 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 931.51 GB PE Size 4.00 MB Total PE 238467 Alloc PE / Size 238336 / 931.00 GB Free PE / Size 131 / 524.00 MB VG UUID qSGaG1-SQYO-D2bm-ohDf-d4eG-oGCY-4jOegU