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."

Comments

Far more practical

[Random BedHead Ed]

This is a much better solution than tape, really. It's predictable that the industry will probably move in this direction, now that the hardware is cheap enough and of high enough capacity to serve this function.

Imagine: instant recovery. Your backup could be a usable image of your live server.

Re:Far more practical

[Servo]

I don't really see it as being all that predictable.

The benefits of having backup to disk is of course speed. But what happens when you have a disaster? Your SOL, because your backup-on-disk system just got toasted too.

The benefits of having backups on tape is that you can send those tapes anywhere. It might not be as quick as sending a file electronically, but when you are talking hundreds of gigabytes of data, it just isn't economical to do anything but tape.

Tape will never die. Hardware may be cheap and high capacity, but transmission costs keep it from being feasible.

You also need to take a look at space utilization. You can put a tape silo into a footprint that gives you much much more capacity per square foot than disk.

Re:Far more practical

[jhoffoss]

This concept raises some issues though. My employer owns two +1TB SANS and has them in separate locations, constantly mirroring from the production to the backup. But if you delete a file off of one, it is also deleted off of the other. So then how do you decide when to actually delete something from the backup, if you want it to serve as a tape backup? Other anomolies can occur as well. A drive died in our backup SAN which brought both SANS (and in turn, all of our servers, which run off of the SAN using fiber cards) to their knees immediately, because they were trying to write bits to that drive (big coincidence, but took us down for over two hours, and it could've been much longer than that...) Still, an interesting concept. But we still take tape backups daily, incrementally through the week and a full backup over weekends. Never put all your eggs in one basket, remember.

Re:Far more practical

[diverman]

Tape can be more reliable, largely because of its time to evolve. It's a more durable solution.

Granted, most current tape systems support more storage than current optical systems. But optical backup systems are gaining popularity. I expect that as they become more popular, they will become cheaper, more reliable, faster, easier, and more spacious... just like every other form of technology that gained popular view.

Tapes have been trust-worthy for some time now, but they are slow and bulky. As the amount of data to backup continues to increase, tape won't be able to keep up. Optical media has progressed in speed considerably over the last few years. I know that some media (CR-R's for example) have hit media thresholds... but they're still MUCH faster than tape at current speeds.

I expect that optical media will continue to improve. In my original post I did state "or something similar", to allow for progress over current optical limitations. My main point really being that tape is dying out. An optical media is becoming a focus for long term storage media, and investment will go into improving upon it.

-Alex

Tape will be with us for a while yet...

[sirwired]

Right now, Sony is shipping Super-AIT tapes. The cartridges are about 3/8 of an inch thick, and each holds 500GB, before compression (which is integrated in the drive hardware). The drive can read or write at 30MB/s, before compression. With typical IT compression of 2:1, you get just under 60MB/s. The cartridge goes for about $150. Just try and get a terabyte of disk for that much. No, the drives aren't cheap, but they get paid off quickly.

Yes, disk is good if you need instant access to your backup, and for small installations of under a couple of TB, using disk backups make sense, but for larger data pools, tape is far more economical.

Also, as mentioned in the article, disk is terrible if you need off-site backups. In addition, a tape library consumes far less power, takes up less space, and produces less heat than a drive array of the same capacity.

Basically, the death of tape has been predicted for years, but it hasn't happened yet.

Re:Offsite?

[kiwimate]

Well, they kind of flitted over it with one sentence:

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.

The article didn't address what to do in this case. Instead, they continued:

As long as this isn't necessary, Dr. Koch's backup system offers some rather unique advantages.

Given that it's hardware-focussed, maybe one can understand this omission, but here in the real world it's still important. So, yes, what does one do if one does need offsite storage? Realistically, I think your suggestion of a big pipe is about the only way. It's hardly feasible to hotswap loads of drives for your offsite storage every morning. (Yes, I know they're using IDE, but think Promise controllers.)

The question then becomes a comparison of the cost of providing for offsite storage in this manner versus the saved cost of replacing your tape library with associated robots, etc.

However, the article also discusses (very briefly) associated costs for specialized backup administrators, delays inherent in recovering from tape backups, etc., so they're not totally unaware of the real-world issue. I suspect they may have chosen to ignore this specific issue because (i) it wasn't an issue in this case study, and (ii) examining it would've been a touch difficult.