Disaster recovery when using a 500GB Raid array

[SarcasticDwarf]

If things go like they are looking right now the company I am working with will have a server holding a number of images. The idea is to put in 3x 500GB SATA drives for the storage in a Raid 5 array that should protect against normal failure.

In addition to this I will want to have a disaster recovery backup. The contents of the server will not change much and frankly a backup of once per month is sufficient. Assuming I have direct access to the server, what would be the best and cheapest method? A tape drive would be an option, but would some kind of software that would replicate the drive onto a removable sata drive be doable and just as good?

 

[taltamir]

it is impossible to have a RAID5 array with only 2 drives.
Read this first: http://en.wikipedia.org/wiki/RAID

Also, think about what you are backing up AGAINST.
RAID will protect you against a hard drive failure. If you use external drives for additional backup what exactly is it protecting against?

External drives (or extra internal drives) make for a poor backup solution (beyond protection against a drive failure).
Burglary? they will also take the external drives to sell them too.
Data thieves? well, what kind of company do you work at and what is your security?
Flood? it will ruin the drive.
Fire? it will ruin the drive.
Virus? it will corrupt data on the drive.

I recommend burning it on write once DVDs (or blu-ray disks) and putting it in a DIFFERENT location, that will protect it against theft, flood, fire, and viruses. And the RAID system will protect against a hard disk failure.

As for your RAID array, use a highly secure one. Like RAID1 or RAID6 for critical data.

 

[SarcasticDwarf]

Sorry, the first part was a typo. That was 3x drives, not two.

As for the raid type, I think I was initially looking at the wrong information. The idea is to use RAID to maintain availability in the event of a single disc failure while using three or fewer drives (cost).

As I mentioned above, the backup is for DISASTER RECOVERY. That means the total loss of the server for any reason. We want to be able to recover all of the images on the server at the time of the backup. Obviously these are stored offsite. Given this, what are my hardware and software options? I mentioned both tapes and hard drives. The tapes are more static, but also far more expensive.

 

[MerlinRML]

The question you're asking is, "what is the right kind of backup?" I think the question you really need to be asking is, "why are my requirements for recovery/restore?"

You've already got a RAID 5 disk solution, so that means you'll be able to handle the basic hard drive failures. You've got a somewhat resilient component in that. Now, in the event that you do have to implement your recovery strategy, what do you need? Is this something you need to be able to pull an all-nighter and be up and running by 8AMor is it more a matter of a few months before anyone would even notice? Answering your time to recover question will help you figure out which backups are not going to work.

Then figure out a rough estimate for storage capacity. Transmitting 2TB over a 1Mb connection to online storage just won't work.

In regards to tape, the initial outlay for a tape drive is quite high. It takes a long time and a lot of tapes before you recoup the initial costs. Not to mention, you need to figure out if your data capacity will exceed your tape capacity, and be prepared to invest in a tape robot or have a night operator able to change tapes for you.

You might look into something like virtual tape which will store your data on hard drives and then make a copy to real tape for sending offsite. These are rediculously expensive for what they are, though, so be prepared for a large price tag.

 

[taltamir]

As Merlin said... How much data do you have?

DVD drive - 30$ for drive. cents per disk. 4.5GB capacity (more expensive 9GB disks available, as well as rewriteable media)
Blu ray drive - 400$ for drive. 8$ per disk (for a 25 pack in newegg). 25GB per disk. rewriteable media can be used as well.
20/40GB Tape drive (uncompressed/compressed) - 300$ (requires scsi). 6-7$ per tape.
36GB/72GB tape drive - 440$. tapes not actually sold on newegg... I found some place selling them online for 15$ each.
400 / 320 / 1.6TB tape drives - 1000-2000$. tapes hard to come by but they seem to be about 50$... speed measured in things like "43.2 GB/hr"...
Tapestry Media (holographic disk) 300GB - 18,000$ per drive. 180$ per rewriteable disk (only disk available right now). 800GB and 1.6TB models in the works...


I wonder about that "compressed" stuff in tape drives... worries me a bit...
Anyways, tapes are slow and sequential. But for the uber storage they are the most sensible route... But MOST cases don't require uber storage... There is nothing wrong with backing up to DVDs if they fit your budget...

http://www.newegg.com/Product/...ion=tape+drive&x=0&y=0

 

[SarcasticDwarf]

As mentioned, we are looking at 500GB of data to recover. That pretty much rules out optical media drives (even BR would be something like 20 disks per month). Transmitting over the net would not work as the bandwidth just is not capable of doing it in a reasonable time period. As I see it the options are really either tape drives or hard drives (though I could be missing something).

The advantages of hard drives are also the disadvantages to tape. The drive would require only a single drive (~$200) and would therefore be fast an easy. Assuming there is software to support it someone (there is no IT staff at this organization) could drop in and put the drive in and start the process then come back after lunch and grab the finished product. By the way, would a standard sata drive tray work or would different hardware be needed?

Tapes are a more stable drive and less prone to failure but are also much more expensive (say 25 or so tapes at $15 plus at least $300 for the drive) and would require a major time commitment to swap them out.


Obviously the idea here is not to eliminate ALL risk (impossible), but two copies (two most recent months) plus the RAID array should be sufficient. The idea here is to just keep the cost REASONABLE in this context. Spending as much on the backup solution as the server just is not going to fly.

 

[taltamir]

MMmm... Yea, I think hard drive would be best... if you only need to back up 500GB... get an external 500GB HDD or two with firewire 800. Bring one each week from the other location. Copy all the data to it (using software you could do a "copy only new data" operation, which could take mere minutes). And then take the drive back to the offsite location!

www.secondcopy.com is what I use for my backup. it is cheap and simple and all you really need.