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Backup strategy - RAID 1 vs. RAID 5

O

oktane

Member

I've been "flying without a net" for some time now, with tons of data and no regular backup solution. Every once in a while, I backup some data to DVD-R. However, after having some errors pop up on my hard drives, with a few digital photographs getting corrupted, I need a fast and reliable backup solution.

Should I use an "on-board" or "out-board" backup solution? For example, I could add a RAID5 controller card to my primary computer, and shove 3-4 SATA drives in there. The benefit would be faster access to data, less expense, not having another bump in my electric bill from having another PSU sucking 400W all day long. The downside is if I had a virus, malicious program, or bizarre hardware event, I could lose all data (including the redundant backup).

I could put the drives in my old PIII 700MHz 1GB RAM, Cheetah X15, which is more of a light duty machine, but still used for more than backup. Or I could go with a dedicated backup machine.

Or I could buy a ReadyNAS server. I like the small size, the fact it is only used for backup eliminating some risk, and the auto expandability of X-Raid. However, it is costly ($600 base + drives).

The other thought is, do I even need RAID5? It adds a lot of comlexity and cost. I could get a RAID5 controller ($300) + 250GB ($100) x 3 hard drives = $600 for 500GB redundant storage. Or a ReadyNAS ($600) + 250GB ($100) x 2 = $800 for 250GB redundant storage.

Even cheaper, I could skip RAID5, use an on-board RAID 0/1 controller, and RAID1 (mirror) two 300GB ($80 after rebate for first, $130 for second) = $210 for 300GB storage, without much complexity. Or two Hitachi 500GBs. Or a pair of 400GB's, etc.

What do you recommend?

Thanks
 
RAID != backup. For a good backup solution, it's for decreasing down time amidst drive failure. That said, for backup, I'd get a 250gb hard drive or two, and image your OS drive onto it, and backup your other data to it.

However, if you are doing RAID, this is the formula that seems to work for most people:
2 drives = RAID 1
3+ drives = RAID 5.

Of course, your individual needs and whatnot might change that, but that is how I will start my input....
Tas.
 
Raid5 can give you increased performance at a price ($$$$), plus it adds redundancy to protect from drive failures. The problem is the increased power consumption (4+ drives running all the time) and cost.

Raid 1 (On-board) gives you a nice mirrored set, to offer redundancy to protect from drive failures. Raid 1 offers no performance advantage over a single SATA/PATA/SCSI drive, but it is really cheap now.

Either option is good, but Raid 1 is much cheaper to implement and run.

Something to consider though is viruses/rootkits/software failures. What "off drive" backup system will you employ? Burning to DVD-R's on occassion is one route, but it takes time (especially for spanned multi disk data images).
 
My "off drive" system would be a lightly used computer with the RAID 1 mirror, mapped as a network drive. I'm assuming whatever virus hits my main computer will not have time to make it to the backup computer before I discover a problem. What backup methods do you all use?
 
i bought a XFX SATA 5Port raid card with 5 Maxtor 300 SATA150. It's running Raid 3 (striping feature of raid 0 plus redunancy of raid 5). have been really happy with performance so far although nothing has crashed so i can't attest how easy it would be to recover. the best part of the Raid card is XP doesn't need drivers. XP recognizes it as a drive.

prices when i bought it at newegg about 4 weeks ago.

XFX 5Port SATA Raid PCI... 239.99
5x300GB Maxtor... 134.00 each
 
A good RAID card, running RAID-1, will use the second drive when it reads- so it will have a performance increase. Most cheap cards and probably onboard RAID won't do this.
 
You know, I think non-onboard (I hate to say external) RAID card are wroth it just for their other features and capabilities... Online expansion and RAID array migration are so nice.
Tas.
 
back up to a separate hard drive on a schedule. don't use RAID for backup, or you'll regret it when you delete something you didn't intend to delete.
 
Originally posted by: oktane
My "off drive" system would be a lightly used computer with the RAID 1 mirror, mapped as a network drive. I'm assuming whatever virus hits my main computer will not have time to make it to the backup computer before I discover a problem. What backup methods do you all use?
Click to expand...

I burn my daily back-up set (I use Backup app that microsoft bundles with Xp Pro. Full backups of specified directories) the to a DVD-RW weekly (basically "my documents" and files I care about, currently using 2/3 of the capacity of a DVD-RW. I have 3 disks in rotation.) My MP3 collection is based on CDs I own, so if I lose it, it's not a big deal.

 
I have a dedicated Athlon XP 3000+ machine with 1 Gig of memory, and SATA II 4 -port RAID card with 2x Seagate 7200.7 (w/ NCQ) (I am adding 2x drives soon). I use this machine as my dedicated Network Attached Storage (NAS).

A very very good RAID setup is RAID 0+1. This allows for the redundancy of RAID 1 with the (almost) same performance of RAID 0. Many large companies are using this solution since drives are so cheap. In addition, in a 4-drive RAID 0+1 setup, you can lose 2 drives and still keep your data. In a 4-drive setup using RAID 5, you can only lose 1 drive. Botton line: Using RAID 1...if you have the extra money, use RAID 0+1 for the added performance. Check this website out...:thumbsup:

http://www.pcguide.com/ref/hdd/perf/raid/levels/multLevel01-c.html
 
I mispoke a bit about losing 2 drives in RAID 0+1... check this out:

RAID 0+1
A RAID 0+1 (also called RAID 01, although it shouldn't be confused with RAID 1) is a RAID used for both replicating and sharing data among disks. The difference between RAID 0+1 and RAID 10 is the location of each RAID system? it is a mirror of stripes. Consider an example of RAID 0+1: six 120GB drives need to be set up on a RAID 0+1. Below is an example where two 360 GB RAID 0s are mirrored, creating 360 GBs of total storage space:

RAID 1
|
/-----------------
| |
RAID 0 RAID 0
/-----------\ /-----------
| | | | | |
120GB 120GB 120GB 120GB 120GB 120GB
A1 A2 A3 A1 A2 A3
A4 A5 A6 A4 A5 A6
B1 B2 B3 B1 B2 B3
B4 B5 B6 B4 B5 B6
Note: A1, B1, et cetera each represent one data block.
where the maximum storage space here is 360GB, spread across two arrays. The advantage is that when a hard drive fails in one of the RAID 0's, the missing data can be transferred from the other array. However, adding an extra hard drive requires you to add an additional hard drive to balance out storage among the arrays.

It is not as robust as RAID 10 and cannot tolerate two simultaneous disk failures, if not from the same stripe. That is to say, once a single disk fails, all the disks in the other stripe are each individual single points of failure. Also, once the single failed disk is replaced, in order to rebuild its data all the disks in the array must participate in the rebuild.

To add to the confusion, some controllers that run in RAID 0+1 mode combine the striping and mirroring into a single operation. The layout of the blocks for RAID 0+1 and RAID 10 are identical except that the disks are in a different order. To the smart controller this does not matter and they gain all the benefits of RAID 10 but are still labelled as only supporting RAID 0+1 in their documentation.

[edit]
RAID 10
A RAID 10, sometimes called RAID 1+0, or RAID 1&0, is similar to a RAID 0+1 with exception that the RAID levels used are reversed?RAID 10 is a stripe of mirrors. Below is an example where three collections of 120 GB RAID 1s are striped together to add up to 360 GB of total storage space:

RAID 0
|
/-----------------------------
| | |
RAID 1 RAID 1 RAID 1
/------\ /------\ /------
| | | | | |
120GB 120GB 120GB 120GB 120GB 120GB
A1 A1 A2 A2 A3 A3
A4 A4 A5 A5 A6 A6
B1 B1 B2 B2 B3 B3
B4 B4 B5 B5 B6 B6
Note: A1, B1, et cetera each represent one data block.
One drive from each RAID 1 set could fail without damaging the data. However, if the failed drive is not replaced, the single working hard drive in the set then becomes a single point of failure for the entire array. If that single hard drive then fails, all data stored in the entire array is lost.

Extra 120GB hard drives could be added to any one of the RAID 1's to provide extra redundancy. Unlike RAID 0+1, all the "sub-arrays" do not have to be upgraded at once.

RAID10 is often the primary choice for high-load databases, because the lack of parity to calculate gives it faster write speeds.

 
i just use a large HDD in an external USB2 HDD case, i back up docs, mp3s and Pics, only turn it onwhen i need to make large changes or additions
 
Originally posted by: oog
back up to a separate hard drive on a schedule. don't use RAID for backup, or you'll regret it when you delete something you didn't intend to delete.
Click to expand...
Or if your data gets corrupted, it's corrupted on both your RAID 1 HDs. :roll:

 
I know exactly what I want, basically RAID 1 in an external NAS box with room for 4 DIY drives. That should be relatively cheap but I've never found something affordable.
 

I think I've decided on some sort of NAS device. The question is should I "roll my own" or buy a ReadyNAS.

One thought is to go with a cheap Dell 9100 and add a couple SATA drives, without even using RAID. I may add RAID to my primary computer, on the main working drive.

As for backup, is there a program available for Windows XP that can "pull" data off other networked folders? I want the external computer to backup important directories every night, and automagically create DVD-RW backup sets spanning multiple disks at the push of a button.

DVD+-RW drives are cheap, and I have a server case I could stick 6 drives into. If only there was appropriate software to backup 6*4.7gb=28.2GB at a time. Or I could wait for BlueRay.

 
6 DVD-RWs??????? Are you nuts? RAID card=$80, 2x Seagate 7200.7 160GB=$200

Total=$280

Don't make this complicated.
 
RAID is NOT a secure backup plan - theoretically, all the drives on a given controller could be killed by the same malfunction. I suggest using a firewire external hard drive (or rotate several thru the external enclosure using a mobile rack). Make both file by file and image backups to have both the quickest restore speed and the most secure of backups - like a belt and suspenders...

.bh.
 
RAID is not a secure backup plan??????? Tell that to your bank, your credit card company, the IRS, Yahoo, MSN, Google, etc.

RAID is the most secure way of maintaining data integrity. Period. End of story.

Firewire external hard drive???? Single point of failure...

Zepper, not sure what you do, but I WORK as as computer engineer with servers, NAS, etc, etc. I am quite sure I know what I am talking about...BUT....if you think I am wrong, go ahead and ask anyone else in this forum what they think about the security of RAID.
 
RAID is for preventing downtime due to individual drive failures - anyone that uses RAID should still be doing backups to separate media - or perhaps a second mirror in an off-site location would be OK - assuming the programs and data are mission critical. It all depends on how risk-averse the management is and the quality of the advice they are getting from their IT staff whether they do that or not. That is my opinion based on 25+ years of PC experience and I'm sticking to it.

.bh.
 
Originally posted by: SnoMunke
RAID is not a secure backup plan??????? Tell that to your bank, your credit card company, the IRS, Yahoo, MSN, Google, etc.

RAID is the most secure way of maintaining data integrity. Period. End of story.

Firewire external hard drive???? Single point of failure...

Zepper, not sure what you do, but I WORK as as computer engineer with servers, NAS, etc, etc. I am quite sure I know what I am talking about...BUT....if you think I am wrong, go ahead and ask anyone else in this forum what they think about the security of RAID.
Click to expand...


Raid does not protect againt data corruption, if you're data is corrupted, you can have a million raid and it wont help.

Have you ever had a raid 5 array with more than 3 drives and have 2 drive fail ?

Raid 5 with large array are also dangerous. Chances of 2 drives failing are low but guess what, it does happen.
 
Originally posted by: SnoMunke
RAID is not a secure backup plan??????? Tell that to your bank, your credit card company, the IRS, Yahoo, MSN, Google, etc.

RAID is the most secure way of maintaining data integrity. Period. End of story.

Firewire external hard drive???? Single point of failure...

Zepper, not sure what you do, but I WORK as as computer engineer with servers, NAS, etc, etc. I am quite sure I know what I am talking about...BUT....if you think I am wrong, go ahead and ask anyone else in this forum what they think about the security of RAID.
Click to expand...


Whoa there boss.. RAID protects against downtime and provides more performance for disk access. As stated before RAID != backup. I lost a 10 disk RAID-5 Array 2 weeks ago because the SCSI backplane died. Luckly, my trusty 200Gb tape backup was there to pick up the slack.

For pure backup needs (not performance) RAID is not the best measure. An external USB hard drive will suit you fine. Get 2 and alternate them in case you need to roll back to a previous backup.

2x$50 - USB2.0 SATA External HDD Case I have one of these and it's great. I like having the fan in the bottom for heat issues.
2x$82 - Maxtor DiamondMax 10 160Gb HDD
------------
$264 total
 
RAID is nice if you don't want any downtime.

The easiest solution for me has been to simply plug in another SATA HD in my PC.
I installed Acronis Image Software to schedule daily backups. It will make a full backup and then appendages to the full backup to save space or whatever I choose. I can also backup over a network, which I like since I have 2 PCs. The software runs by itself. It will backup to the backup hard drive in each PC. Than each PC will make another backup of itself to the other PC. This solution allows me to have 2 backups on each PC in the event that my hard drives crash or my OS gets hosed I can recover my data from the other PC.

At work, I implement the same thing. I run Acronis on 5 PC's. All the data gets backed up to an external USB over a network. Then I make a mirror image of that to a 2nd external HD that way I always have 2 copies of the same data. I take one external HD home in case of a fire or theft. Simple, easy and works.
 
just having two regularly scheduled backups on external harddrives- one weekly and one daily, should be enough, and is easily handled by Norton Ghost. Since I chose to use laptop HD with 2.5'' enclosures, you won't need any more power than what is drawn from the USB port, the HD doesn't spin up unless in use, and laptop HD's are slower, but are better built to take impact.
 
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