On Fri, 2013-07-05 at 13:10 +0200, David Brown wrote: > I apologise if this is preaching to the converted. When you are > concerned about data resilience, RAID is only part of the answer - I > just want to make sure you have considered everything else. Sure... I make regular complete backups, on different types of storage media (magnetic vs. optical - yes I do fear very strong coronal mass ejections ;-) )... being placed in different locations (even different cities ;) > The main benefit of RAID is availability - you don't have downtime when > a disk fails. It also ensures that you don't lose data that is created > between backup runs. But it is not the solution for data safety and > reliability - that is what backups are for. Sure... > You need to look at the complete picture here. What are the risks to > your data? Is a double disk failure /really/ the most likely failure > scenario? Have you considered the likelihood and consequences of other > failure types? In my experience, user error is a bigger risk to data > loss than a double disk failure - I have more often restored from backup > due to someone deleting the wrong files (or losing them due to slipping > when dragging-and-dropping) than from disk problems, even with non-raid > setups. Hehe... I once accidentally mke2fs'ed (instead of fsck) over my main personal data fs (and fucking e2fsprogs don't check for existing fs/containers, AFAIK till today)... and back then my most recent backup was really old... like 2 years or so... I invested like 2 weeks of ext4 forensic and managed to basically recover all of the data out of the overwritten fs... ;) > Raid will help if one of your disk dies, but it will not help against > fire or theft, or hardware failure on the NAS, or software failure, or > user error, or malware (if you have windows clients), or power failure, > or any one of a number of different scenarios. > > So depending on your circumstances, you might get better "data > security/resilience" by putting the extra disks in a second machine at a > second location, or other mixed primary/secondary arrangements. sure... see above... I do have a good backup strategy now :) Anyway... for the daily growth of data... RAID does a good "backup-like" job in helping me against disk failures... since I simlpy can't backup everything every day... Cheers, Chris.
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