If I want 2TB of storage that I want to always be backed up, is RAID 1 or 5 better?

[BigToque]

If have 1TB hard drives and I use RAID 1, I would need 4x1TB and each drive would be mirrored.

If I use RAID 5, I use 3x1TB. 2 of the 3 drives gives me the 2TB I'm looking for and the 3rd drive would be used to rebuild the array when I installed a new drive. (Is this correct?)

Which is a better option for a home user?

The only thing I've got backed up on these drives are my movies and music. It is just a pain in the ass to rip and encode.

 

[nickbits]

I would recommend a seperate set of drives in a different machine. That way you are coverded by more than just drive failures.

But out of RAID1/5 I would pick 1.

 

[TheKub]

Been said many times here, RAID is not a backup, its redundancy.

That being said RAID 1 is simpler and therefore more recommended but 5 is cheaper.

 

[RebateMonger]

The easiest and safest way to prevent data loss would be to NOT use RAID, and to back up the data onto external hard drive(s). If you do it that way, make periodic backups, and keep the backup drive(s) unplugged when not in use, it'd be VERY tough to lose a significant amount of your movies and music.

As always, having backup disks does nothing if you don't use them. And be sure to periodically test your backups (restore some files from them) to be sure that you are actually making USABLE backups. Also, double check that you are backing up what you think you are backing up.

 

[LS8]

RAID5 is the safest online storage option, period.

Backing up to hard disk isn't recommended. Backups should be made to some form of hard media, be it tape, CD, DVD, whatever.

That said, for home use I don't bother with hard media backups. I've never lost a drive in my home RAID5 solution - not that it can't happen but even if it does my data isn't gone, just toss in a new drive and let the array rebuild.

 

[Madwand1]

Originally posted by: LS8
RAID5 is the safest online storage option, period.

Backing up to hard disk isn't recommended. Backups should be made to some form of hard media, be it tape, CD, DVD, whatever.

Nonsense. RAID alone is not a backup.

Non-HD backups are not really viable for significant data volume at consumer budgets, and HD backups work just fine, generally giving the best performance and cost / capacity.

 

[JackMDS]

Originally posted by: RebateMonger
As always, having backup disks does nothing if you don't use them. And be sure to periodically test your backups (restore some files from them) to be sure that you are actually making USABLE backups. Also, double check that you are backing up what you think you are backing up.

:thumbsup:

I use Acronis TI for back up. When ever the back up is over to press on the Validate option and in few minutes it Validates the BackUp.

In any case all of the RAID business for Client computers (None Real server) is a Nonesense issue that is mainly based on Social Desirability rather than sound technological solution. It is already slowly slowly disappearing from the functional scene.

 

[RebateMonger]

Originally posted by: LS8
RAID5 is the safest online storage option, period.

I've seen data lost from RAID5 arrays many times. I've seen a couple of multi-drive failures, I've seen a corrupted Parity stripe on $10,000 iSCSI array. And I've seen many cases where a disk failed and nobody noticed and a second disk failure lost the entire array.

Just last night, I looked into a backup problem on a client's server and found that one of the three disks in their RAID5 array had gone offline months ago. That RAID card (Dell PERC 5/i) doesn't have an audible alarm, the original server installer hadn't installed Dell's Server Management software, and the Dell PERC 5/i doen't pass S.M.A.R.T. messages through to the OS. A second drive failure would have lost their entire server. Fortunately, they have daily backups of the entire server (on external hard drives), plus online (Internet-based) backups of "critical" data files.

I don't trust ANY disk or redundant array with the only copy of important data. Backups can be online, to hard disks, or to tapes. All have their pros and cons. The LEAST trustworthy is CD/DVD backups and I'd never use them for anything important.

 

[WaitingForNehalem]

Get a 2TB hardrive. http://www.newegg.com/Product/...%201035313499&name=2TB

 

[s44]

RAID 6

 

[Mark R]

Your options:
RAID 0 + 1: A pair of 1 TB drives is striped in RAID 0, second pair acts as a mirror. 100% overhead (4 TB of drives required for 2 TB storage). Will always survive a single drive failure. May survive a double drive failure (but not if 1 drive from each stripe goes).
RAID 5: Data is striped over 2 drives, with the 3rd drive holding recovery data. 50% overhead. Will always survive a single drive failure. Will never survive a double drive failure.
RAID 6: Data is striped over 2 drives, recovery data is stored on 3rd and 4th drives. 100% overhead. Will always survive a single or double drive failure. Rarely supported except on very high end RAID controllers.

Other points:
Multi-drive failures are more common than you would expect based on the failure rates of single drives. Usually because arrays are made with the same model drives, bought at the same time, from the same manufacturing batch and exposed to the same conditions. Also, one drive failure could damage others. This happened at work recently - one hard drive in a RAID array died due to a bearing failure. Now imagine the platters in that drive spinning at 7200 rpm on a disintegrating bearing; the vibration was so severe that it actually crashed the heads in a neighboring drive.

RAID is not backup. RAID is designed to keep you going if there is a mechanical problem - when access to your data is time critical, that's when you need RAID. E.g. a file server in an office used by 20 people needs RAID, because if the drive fails, you're going to have to pay 20 people to scratch their ass for several hours until you fix the server and restore the data. RAID does precisely nothing for human error (deleting the wrong file) or malicious software (e.g. virus attack deleting or corrupting your documents). All it does is keep a faithful copy of the fact that you deleted your data. In practice, it is human error that is the more likely cause for data loss than hard drive failure.

That's why you need a good backup solution - the easiest way to do it at home is to use an external hard drive.

 

[RebateMonger]

Originally posted by: WaitingForNehalem
Get a 2TB hardrive. http://www.newegg.com/Product/...%201035313499&name=2TB

I buy the latest/biggest hard drive for backups. When your main storage drives become too small, make the big backup drives the main storage drives and buy larger backup drives. The original "small" (1 TB, in this case) storage drives can usually be moved to other desktop computers as replacements or upgrades.

 

[redbeard1]

Originally posted by: s44
RAID 6

Seconded.

Or, Raid 1 or 5 with a hot spare. This may also be a feature that would be found on higher quality raid cards.

 

[Fox5]

I'd say RAID 5 over RAID 1. The chance of two simultaneous hard drive failures is low, and RAID 5 is cheaper on the hard drive space.
But a real external backup system would be better if you want to guard against data loss. Windows even has built in automatic backups.

 

[KentState]

I would do RAID 5 and pay for an online backup solution if possible. I've been using Mozy for example and have had very good luck with them. Yes, it will take some time to catch everything up, but it's good for important stuff like photos and documents.

 

[Fox5]

Originally posted by: KentState
I would do RAID 5 and pay for an online backup solution if possible. I've been using Mozy for example and have had very good luck with them. Yes, it will take some time to catch everything up, but it's good for important stuff like photos and documents.

Online backup is only suitable if you're only backing up some things. A complete image would take FOREVER over the net.

 

[BlahBlahYouToo]

Originally posted by: RebateMonger

Originally posted by: LS8
RAID5 is the safest online storage option, period.

I've seen data lost from RAID5 arrays many times. I've seen a couple of multi-drive failures, I've seen a corrupted Parity stripe on $10,000 iSCSI array. And I've seen many cases where a disk failed and nobody noticed and a second disk failure lost the entire array.

Just last night, I looked into a backup problem on a client's server and found that one of the three disks in their RAID5 array had gone offline months ago. That RAID card (Dell PERC 5/i) doesn't have an audible alarm, the original server installer hadn't installed Dell's Server Management software, and the Dell PERC 5/i doen't pass S.M.A.R.T. messages through to the OS. A second drive failure would have lost their entire server. Fortunately, they have daily backups of the entire server (on external hard drives), plus online (Internet-based) backups of "critical" data files.

I don't trust ANY disk or redundant array with the only copy of important data. Backups can be online, to hard disks, or to tapes. All have their pros and cons. The LEAST trustworthy is CD/DVD backups and I'd never use them for anything important.

what kind of IT/systems group does not setup alerting for hardware failures?

 

[Red Squirrel]

Raid 5 if you are willing to buy 3 drives (and best bang for the buck tbh as you will get more space) or raid 1 if you only want to buy 2 drives.

Raid != backup though, so you should still do regular backups with rsync of that raid array.

 

[zerogear]

WHS. :]

 

[Zap]

Originally posted by: RebateMonger
The easiest and safest way to prevent data loss would be to NOT use RAID, and to back up the data onto external hard drive(s).

This.

No level of RAID will protect your data against Windows partition corruption, viruses, accidental deletions, sabotage, electrical surge, theft of computer, etc.

"Having a backup" means having more than one copy of the data. Doesn't matter whether it is on CD, external HDD, tape drive, server, online... you just need more than one copy (and a whole bunch if you're paranoid). Also for the paranoid (or very important data) you need to store backups at a different physical location. Thus, if your house burns down you know your data is safe elsewhere.

One big stumbling block of backing up data is that it is often a chore to do so. External HDDs make it easier, so that's why it is often recommended. Just don't drop it or knock it over.

 

[RebateMonger]

Originally posted by: BlahBlahYouToo
what kind of IT/systems group does not setup alerting for hardware failures?

I see it all the time. Almost every new office I visit (accountants, lawyers, doctors) isn't being monitored and isn't being backed up correctly. That's reality in the home and small business world. Most of them get away with it, at least for a few years. Eventually, probability catches up.

 

[Red Squirrel]

Originally posted by: RebateMonger

Originally posted by: BlahBlahYouToo
what kind of IT/systems group does not setup alerting for hardware failures?

I see it all the time. Almost every new office I visit (accountants, lawyers, doctors) isn't being monitored and isn't being backed up correctly. That's reality in the home and small business world. Most of them get away with it, at least for a few years. Eventually, probability catches up.

Yep, it's sad but it's seen a lot.

In fact, my home backup solution (which is not perfect) is better then most places I've seen. Most of my backups are a mirror of the source (not raid mirror, but copy / rsync mirror) while the most important stuff is on a rotation bassis. Usually weekly and monthly.

One of our clients has NO backups, and they are a rather big and important company. That will soon change though, we are in middle of installing a new SAN along with tape backup system and whole shebang. Problem is, we really should backup the old SAN before we start screwing around with migration, but we wont.

 

[glugglug]

Originally posted by: LS8
RAID5 is the safest online storage option, period.

Backing up to hard disk isn't recommended. Backups should be made to some form of hard media, be it tape, CD, DVD, whatever.

That said, for home use I don't bother with hard media backups. I've never lost a drive in my home RAID5 solution - not that it can't happen but even if it does my data isn't gone, just toss in a new drive and let the array rebuild.

RAID1 is clearly safer than RAID5. In fact, with drive sizes (and enterprise array sizes) increasing, and the bathtub curve making drive failures likely to be clustered together in time, there have been studies showing that in the time it takes for a newly swapped in drive to get imaged as the new parity after a drive failure in a typical RAID5 configuration, you have better than a 50/50 shot of a bad block occurring on another drive, in which case you are screwed. This is why RAID6 was created.

 

[RebateMonger]

Originally posted by: glugglug
..... there have been studies showing that in the time it takes for a newly swapped in drive to get imaged as the new parity after a drive failure in a typical RAID5 configuration, you have better than a 50/50 shot of a bad block occurring on another drive, in which case you are screwed.

One of the articles you are talking about.

 

[Fullmetal Chocobo]

Originally posted by: zerogear
WHS. :]

Is there a such thing as Epic THIS.?

RAID != backup. And RAID 5 does corrupt and fail (I've had it happen due to bad PSU). If you want a 2TB backup, get a 2TB external, and use the thing. Hell, buy two and rotate them out, so that you have offsite backup as well. And DVD is not a viable primary backup solution either.

My configuration: WHS (RAID 1 for boot drive, everything else handles by WHS) + external + flash drive for critical data.