is it possible to start a mongodb instance when some collection files are missing from the WiredTiger data folder? Only some collection files missing, ALL other files from the data path are present.
I tried this on a 3.4 instance, but mongo would not start because of the missing files. I now solved my issue in a different way, but I’m curious to know anyway, just in case I will need this again in the future.
On a more general topic, I have to manage this 3.4 instance; we currently cannot upgrade to a more recent version. The instance has some huge collections, so an idea for backup was to do frequent backups via lvm snapshots + data files copy skipping the largest files, and copy the large files less frequently instead, e.g. during weekends.
But is such a backup usable in case of disaster recovery? As reported above, I was not able to start the db without some collection files (the largest ones). I also tried replacing the missing files with copies from a different backup, but again it did not work, mongodb complained about wrong checksums and so on.
I’m now going back to backups using mongodump, which I mostly used before. I’m only not sure how fast and reliable can be the mongodump of a 1TB collection…
Thanks for any info.