Hello, Bill. On Sun, Feb 11, 2024 at 10:14:49 +0800, William Kenworthy wrote:
> On 10/2/24 23:56, Alan Mackenzie wrote: > > I was wanting to do a pretty full build of my Emacs working repository. > > This involved first purging al *.elc files. The way to do this is > > $ find . -name '*.elc' | xargs rm > > . But for some reason, I typed > > $ find . '*.elc' | xargs rm > > . I even carefully checked it before pressing RET. However, press it I > > did, instantly deleting all files in my working directory. OUTCH! > > So, I fell back on my backup from last Sunday. After about 1½ hours > > trial and error, I had my source files as of last Sunday back again, > > though git could have been more helpful than it actually is. > > Thankfully, I had Emacs open, with all the files modified since Sunday > > in buffers. So, I laboriously worked through Emacs's buffer list, > > saving those ones I'd since changed. > > I lost all my timestamps on the files, and lost all my Emacs backup > > files (things ending in ~ which Emacs constantly makes). But my > > software builds and runs. > > It could have been a lot worse. Boys and girls, don't use > > $ find .... | xargs rm > > unless you really know what you're doing. And even then, it's probably > > better not to. ;-( > > It occurred to me fairly quickly after that press of RET that I could > > have done well with a COW snapshot facility, something which has been > > discussed at length on another recent thread. I even have LVM on my > > machine for its RAID capabilities. But I've never bothered before. I > > mean "I'm too careful", amn't I? ;-( At least I do a weekly backup, > > though. > > So, in the end I managed to recover fairly well, thankfully. > No, you don't need a snapshot system - you need a proper backup system > that stores the proper metadata. I remembered after sending my original post that I stored the timestamps of all the files in a file called timestamps.txt. So a quick sed script invocation on this file, and I had my timestamps back again! > When I was experimenting with snapshots (btrfs and moosefs) at > different times I lost everything a few times with filesystem > corruption which meant I lost the snapshots too. > Snapshots are NOT safe backups - treat them as a convenient copy ... I was thinking of a snapshot more as an addition to backups, not an alternative. Such would have made it easier for me to recover yesterday. A backup on the same medium as the filesystem isn't a backup at all. I've never had a disk drive or SSD fail on me yet, but I'm not pushing my luck. > BillK -- Alan Mackenzie (Nuremberg, Germany).
