The backup verification cheat sheet

Quick reference

Archive

$tar -czf /backup/etc.tgz /etc
$tar -tzf /backup/etc.tgz | head
$aws s3 cp etc.tgz s3://bkp/etc/
$sha256sum /backup/etc.tgz

Test

$tar -xzf /backup/etc.tgz -C /tmp/r
$tar -df /backup/etc.tgz
$sha256sum -c SHA256SUMS
$diff -r /etc /tmp/r/etc | head

Retention

$find /backup -mtime +30 -type f
$find /backup -type f -ls
$logrotate -d /etc/logrotate.d/bkp
$aws s3 rm s3://bkp/old/ --dryrun

Cost

$du -sh /backup/*
$du -h --max-depth=1 /backup
$aws s3 ls s3://bkp --recursive --summarize
$aws s3 ls s3://bkp --recursive

Explained

Archive

tar -czf /backup/etc.tgz /etc builds the archive. tar -tzf /backup/etc.tgz | head lists it without writing a file. aws s3 cp etc.tgz s3://bkp/etc/ moves the copy off the host. sha256sum /backup/etc.tgz prints the digest, and the digest belongs beside the archive, not in a chat message.

Test

tar -xzf /backup/etc.tgz -C /tmp/r extracts to a scratch directory. tar -df /backup/etc.tgz compares the archive with the filesystem. sha256sum -c SHA256SUMS verifies the digest. diff -r /etc /tmp/r/etc | head shows what differs.

Retention

find /backup -mtime +30 -type f lists what is older than the policy. find /backup -type f -ls shows the size and the path. logrotate -d /etc/logrotate.d/bkp tests the rule without moving a file. aws s3 rm s3://bkp/old/ --dryrun shows what a delete would remove.

Cost

du -sh /backup/* shows the big directories. du -h --max-depth=1 /backup shows the split. aws s3 ls s3://bkp --recursive --summarize totals the objects. aws s3 ls s3://bkp --recursive lists every object and its size.

In one line

Open one archive

$tar -tzf /backup/etc.tgz | head