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621 points sebg | 1 comments | | HN request time: 0.198s | source
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stapedium ◴[] No.43717547[source]
I’m just a small business & homelab guy, so I’ll probably never use one of these big distributed file systems. But when people start talking petabytes, I always wonder if these things are actually backed up and what you use for backup and recovery?
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ted_dunning ◴[] No.43720813[source]
It is common for the backup of these systems to be a secondary data center.

Remember that there are two purposes for backup. One is hardware failures, the second is fat fingers. Hardware failures are dealt with by redundancy which always involves keeping redundant information across multiple failure domains. Those domains can be as small as a cache line or as big as a data center. These failures can be dealt with transparently and automagically in modern file systems.

With fat fingers, the failure domain has no natural boundaries other than time. As such, snapshots kept in the file system are the best choice, especially if you have a copy-on-write that can keep snapshots with very little overhead.

There is also the special case of adversarial fat fingering which appears in ransomware. The answer is snapshots, but the core problem is timely detection since otherwise you may not have a single point in time to recover from.

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1. ghugccrghbvr ◴[] No.43728986[source]
Disaster at all?