How do you handle HD backups?

[syk]

Well. Obviously I was thinking about how I want to handle backups in case another HD would die on me. How do you do keep your stuff from vanishing into the data nirvana?

[Monoriu]

Flash drives.

[DGuller]

Prayer.  Unfortunately, since I am an atheist, it's not very effective.

[Grey Fox]

Raid is not for Backups!

[syk]

Raid is not for Backups!

I only recently took notice of RAID systems at all, please explain.

[Baron von Schtinkenbutt]

Raid is not for Backups!

I only recently took notice of RAID systems at all, please explain.

RAIDs come in several flavors, but there are four primary mechanisms at work in various combinations.

1) Linking multiple disks together to operate as one mount.  The Just a Bunch of Disks (JBOD) scheme associates two or more drives with a single logical volume, then goes across the disks in series as they fill up.  If you have two disks in a JBOD, the first one will be used until filled, then the second will be used.  This scheme only serves to logically connect multiple drives.  Striping (below) also does this, but the purpose is different.  JBOD is not a true RAID.

2) Spreading files across multiple disks in parallel (striping).  Striping is a feature in most RAID schemes, and is one of the two key benefits to RAID.  By splitting files across multiple drives and reading or writing them to all the drives in parallel, the I/O performance is greatly increased.  That's striping's only benefit, I/O speed; in a striped but unmirrored (RAID 1) configuration, losing just one of the drives renders the entire RAID filesystem junk.

3) Keeping an exact copy of every drive in the array (mirroring).  Mirroring is also a feature in most RAID systems, and the other key benefit to RAID.  In a mirroring configuration each drive in the RAID has an exact clone that is automatically updated with the main drive.  In the event of a disk failure, the RAID automatically fails over to the clone (unless, of course, it was the clone that failed).  In the event of a drive failure, the failed drive can be removed (with the system up in hot-swap systems) and the RAID is rebuilt using the working copy.  Mirroring alone (RAID 0) uses exactly two drives, and the capacity will never be greater than the smaller of the pair.

4) Guarding against data errors (parity).  This is rarely encountered outside of scientific, financial, and medical computing.  Parity configurations (RAID 5 and RAID 6) add additional drives that contain parity bits for all the data stored on the main disk pack.  This permits read errors to be identified by the controller so an additional read attempt can be made to correct the error.  This is only intended to compensate for normal errors reading data off the platters, and will not do anything if the drive is actually failing (beyond give you clear indications that it is).

When most people connect RAID and backup, they are thinking of the mirroring capability.  That capability is only intended to guard against disk failure.  The purpose of RAID (Redundant Array of Independent Disks) is to connect multiple disks together to get a logical volume with capacity and performance not obtainable from a single drive, while also dramatically increasing the reliability by having the ability to correct for single disk failures.

RAIDs still get backed up (usually).  A backup is a golden snapshot of a filesystem that can be used to restore all or part of it in the event of a major problem.  Backups are used to guard against:

• Disk failure
  
• Accidental deletion
  
• Virus infestation
  
• Loss or theft of the drive
  
• Catastrophic accident (fire, flood, etc)
  

RAID only addresses the first, and from a different perspective (albeit with the same result).

[Darth Wagtaros]

At work I use a tape backup, differential during the week with one full a month to tape which is shipped to Iron Mountain.
I also have the file server replicated to another location, a two USB hard drives in two locations which files are backed up to daily,  and a bigass new Sun box to take many full backups.

At home I just burn the important stuff to DVD.  I've been around the block enough to not let lost HDs hurt.


RAIDs are not backups.  It is suicide to even consider thinking of it as a backup. 

[derspiess]

Currently I just use an external hard drive, but in a few months I'll have built my Windows Home Server box that will handle all my backups for me.

[viper37]

Well. Obviously I was thinking about how I want to handle backups in case another HD would die on me. How do you do keep your stuff from vanishing into the data nirvana?

External HD.  Soon, online backup too.

[Josquius]

CDs for absolutely vital things when I have enough (photos an whatnot).
External HD normally....though I mostly use it for storage rather than backing up these days.
For important docs I email them to myself a lot so that backs them up too.

[MadBurgerMaker]

I have a couple extra hard drives and also burn various things to DVD.

[HisMajestyBOB]

I've got an external hard drive that I've backed stuff up to.

Unfortunately, now I'm worried that the external HD will get damaged or fail. 

[grumbler]

I have a couple extra hard drives and also burn various things to DVD.

This.