Hard Drives Instead of Tapes?

An anonymous reader writes "Tom's Hardware News weekly news letter has a very interesting article about Dr. Koch of Computertechnik AG who won the contract to build a RAID backup system for the University of Tübingen. Dr. Koch took several standard entry-level servers, such as the dual-Athlon MP, and add modern components and three large-caliber IDE-RAID controllers per computer, and a total of 576 x 160GB Drives."

Surprised it didn't happen sooner

[Dragonfly]

I know of a lot of people (myself included) who use multiple external hard drives in rotation for their backups. Especially now with servers' hard drive capacities growing so fast. I just specc'd out a fileserver for a department at a cash-strapped public institution, and a tape drive big enough to backup the system's disk would have been more than 50% of the cost of the computer. Not to mention the cost of tapes. Instead I set them up with two firewire hard drives. For their needs, the reliability/longevity/cost equation made hard drives the best solution.

Re:Sound fine, but...

[ashitaka]

I don't know about the mega RAID systems descibed in this article but we're doing this with a couple of high-capacity IDE drives in a removable drive cage. The relevant system states and data are backed up to these drives daily. The time to get our databases and files up to running state in a disaster scenario is under three hours.

Re:Far more practical

[diverman]

Yeah, I've seen this trend for a while now. Our backup system is also a large HDD raid setup. And for things that need long term storage, those eventually get spooled to tape. I'm sure long term storage will probably start going the way of DVD optical media or something similar (better capacity more likely).

Yeah, the full usable image would be nice, but would probably require a shutdown for data consistency. The backup strategy would likely be similar to that of an Oracle system cold backup. :)

-Alex

Tape technology not keeping pace...

[jafo]

The unfortunate thing is that tape technology just hasn't kept pace with disc technology. Back in my first job, we were backing up $1,000 20MB drives onto $40 200MB tapes. If that held true, today we would have $4 tapes that would hold around a terrabyte of data...

But, we now have $100 tapes that hold as much data as a $100 hard drive.

We switched over to hard drives for our backups at our (modest) server facility. Late last year we spent $2000 on a system with 600GB of RAID-5 protected storage. That holds current and historic backups, for around 6 months with our current load. We then weekly dump the current data-set off to a removable 120GB hard drive, which we take off-site.

Tapes are SO dead...

It works great.

Sean

Why not Quantum DX-30

[harmless_mammal]

Instead of building a giant kluge, why didn't they buy a few Quantum DX-30s? Each one only takes up 4U, holds 20 drives, and the internal software emulates a tape library so it easily integrates with enterprise backup software from Legato or Veritas. If your environment requires off-site storage, you could attach a tape library to clone the backups and then store the tapes off-site.

Re:Sound fine, but...

[afidel]

Well as the article states this implementation isn't really for offsite There's one aspect in which Dr. Koch's backup system can't keep up with tape solutions: storing the backup medium in another location after the backup has been completed. but it could be done pretty easily. Non-operating shock capacity on the D540X is 300G's for 2ms which is pretty darn good (plastic tape housings might shatter under a similar load). I also like the ultra low failure rate .5% (hmm, this and the data from storage review shows that the D540X and D740X line seem to be some of the most reliable out there...) I know our DAT failure rate was in the same ballpark.

Re:Sound fine, but...

[Bonker]

As someone who works in IT in the financial industry, let me tell you a little bit of what kind of requirements we fulfill. First of all, every system is backed up on a regular basis. For critical systems (systems that handle account numbers in any way), that schedule is daily or even hourly.

All systems have live fail-overs. When not required by law, and they frequently are, such systems are required by the demands of profit. If financial transactions falter for a *second*, it means money lost.

Back-up media is triple redundant and incremental over 5 days. Backup irregularities of any kind are logged, investigated, and acted upon by at least 3 individuals.

Copies of backups are stored both on site and off-site in a secure location provided by our insurance provider. We make frequent trips to this secure location daily in order to deposit backups. These procedures are audited and reviewed on a regular basis by both internal auditors and regulatory board auditors.

Tape is just a little more reliable than IDE in this kind of situation. Tape is going to be more recoverable, even in case of a long drop or serious auto accident between point A and point B. If necessary, teap will also survive shipping better.

Sorry, guys. As reliable as IDE drives have become, they're just not as durable as a tape cartridge. With the sheer amount of backup we keep, it's also significantly cheaper.

Three Words:

[Null_Packet]

Spinning Disk Backups

It's being done all over. Some people are using Network Appliances, some people are using Linux machines. Even Legato, a major player in the backup market supports backup 'staging' to spinning disk to decrease backup windows.

Re:I wouldn't want to support it...

[PerlGuru]

It mentioned it several times spread pretty evenly through the article. The 3Ware controllers switch in the hot backup and that specific drive is replaced. It doesn't directly say but it sounds like the defective drive could be hot-swapped, perhaps a function of the controller? In addition from the rest of the article it would be no problem to take down a single node for the short few minutes to switch out the drive.

Re:Sound fine, but...

[Zathrus]

High end mag tape cartridges store 50GB.

Uh, I think you better look at tapes again. AIT-3 is 100GB uncompressed. Super-AIT is 500GB uncompressed. Transfer rates for Super-AIT are in the 30 GB/s range uncompressed. All of these numbers go up with compression, which is built into the tape drive hardware -- assuming you're storing compressable data.

All in all, they're likely to have a higher sustained transfer rate than IDE drives, and are going to be more reliable, less costly in bulk, and easier to handle.

Of course they're silly for small systems... but that's not what we're talking about at all.

Re:Tape technology not keeping pace...

[JediTrainer]

RAID-5 only requires 3 disks, although you can use more if you want better data protection.

I get the feeling that you understand how RAID-5 works, but your statement is misleading.

With RAID-5 it stores parity data across the array for each piece of information stored. So to store data that would fill N drives, you need N+1 drives for the array (1 drive extra for the parity info).

Adding drives won't protect your data any more (although hot standbys are nice to have). RAID-5 fails if I lose two drives at once. On a 3-drive array, that would mean I'd have to lose 66% of my drives at once to lose my data. On a 10-drive array I'd have to lose only 20% of my drives to lose my data. Having the hot standby drive would be great, because the chances of two drives failing simultaneously are usually low, so hopefully the hot standby would be synched before another drive goes.

A better solution would be to use striping and mirroring together, for maximum redundancy. Costs more, but a lot safer.

Optical tape?

[gweihir]

For some years there have been rumours of optical tapes with capacities in the several hundreds of GB or even several TB per cartridge, but no products that I am aware of so far.

Still I think that this misbalance between tape prices and HDD prices cannot last.

Re:Far more practical

[shotfeel]

The reported shelf life for CD-R is anywhere from 10-100 years depending on the type of dye and who you want to believe.

My understanding was that for tape it is only 5-10 years, but that could very well be out-dated. What is the current shelf life for magnetic tape?

Re:I wouldn't want to support it...

[afidel]

3Ware controllers support hotswap and hotspare, so on failure the data is recreated to the spare so need to rush in replacing the drive (in other words get around to it whenever you have time that week) and then you just unplug the drive and plop in a new one. Plus they have lost a total of 3 drives in the first year, I had to change out tapes every 2 weeks, this is a lot less work =)

Cost effective?

[the kfc avenger]

I can appreciate the appeal of building a massive system from commodity hardware, but it states that the entire system was $435,000. After some rough calculations, a smilar system using apple xserve-RAIDs [apple.com] would run around $300,000, or $135k less before host computer costs, and would most likely be much easier to maintain. Plus, five racks of xserves would look pretty bitchin' :P