WinRAR and backing up in the cloud

2013-03-03 16:29:38

I know there are a lot of very knowledgeable people around here who care about their data, so I though I'd ask here in the off-topic section.

I use WinRAR for archiving a lot of my music and videos. I used to store the archives on CDR and DVD-R, and later on external hard drives. As cloud storage is becoming more common, would you say it is necessary to add recovery data and/or recovery volumes for multi-volume archives when they are going to be stored in the cloud? Or was this just an extra security measure when dealing with unreliable media?

WinRAR and backing up in the cloud

Reply #1 – 2013-03-03 17:32:01

While "the cloud" is far from perfect, from a strictly data corruption perspective it is way more reliable than CDRs or DVDRs.  While it is theoretically possible to design a really stupid and unreliable offsite backup, all the services I have seen have integrity checking built into the service. 

That being said, if you really value your data then a bit of extra protection may be worth it to you.  Obviously adding recovery records increases the size of your backups, so you need to take that into account.  Bigger backups will take longer to transfer which may be a big deal when using a typical home internet connection.

I'd suggest you take a look at par (parity archive).  It's basically the same idea as recovery records in a RAR file without putting your files in an archive.  For things like audio and video files which don't compress well anyway I find it is far more convenient.  As an example, I create a par recovery record for each of my albums and keep it in the same directory with the music files.  Then my cloud backup just backs up the music files and par files together.  Should I need to recover the par files will tell me if the files are unchanged and can fix any potential damage. 

WinRAR and backing up in the cloud

Reply #2 – 2013-03-03 19:13:14

Thanks for the tip, Washu.

To be honest, I've never really understood all of these features, so I have probably been using more than I needed to. 

I guess I'll just skip the recovery records and do my backups to multiple cloud providers, this seems like a safe enough way for me. After all, with different backup solutions, aren't all sorts of files being backed up without any kind of recovery records anyway?

WinRAR and backing up in the cloud

Reply #3 – 2013-03-04 04:20:39

While having backups in multiple locations is a very good idea, it's not the same as a recovery record. 

If by some rare chance a file does get corrupted, unless the file itself has built in error checking you may not know.  Some files like FLACs and RARs have built in error checking and can be checked for corruption.  Other files like JPEGs and WAV do not.  While very often a corruption in such a file is obvious, its not a sure thing.  If a file gets corrupted in a cloud backup or (more likely) gets corrupted on your computer before sending it the damage may not be easily detected.

That being said, given that almost everything involved with any decent cloud backup is going to have error detection the chances of something getting corrupted is extremely slim.  As I said above, the far more likely cause of corruption is on your own PC, specifically by bad RAM.  RAM is one of the few things in a modern computer that does not usually have error detection, at least in consumer PCs.  If you are paranoid then checking your memory with a tool like memtest86 every so often is a good idea.  Contrary to popular belief, hard drives are not a big cause of data corruption.  Hard drives often cause data loss, but almost never corrupt data. 

What recovery records and par files add to all this is error correction.  That is, up to a certain amount of corruption can actually be repaired in addition to simply being detected.  Even if the correction part is not used, they can quickly verify if a file is undamaged, even on files that do not support that natively. 

WinRAR and backing up in the cloud

Reply #4 – 2013-03-04 21:19:35

Once again, thank you.