Slashdot Mirror
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."
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.
There has to be a better way than relying on anything stored in magnetic format, optical I think woudl be preferable, and resistant to EMP.
But as large as harddrives are getting, the demand for backup will still be larger. I don't see this as taking over tape any time soon. People have been talking about how big harddrives are getting and about the demise of tape for a long time.
Just remember, if you can build something like this for backup, you can also build something like this for regular storage... and then what will you do if you need to back it up? Especially if you need to have a 6 month rotating backup...
I'm afraid it will be back to tape then...
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.
One thing about tape systems that I didn't see mentioned was the portability of the media. Data recovery is still impossible if your backup burns up along with your server. I don't see anyone rolling one of these out to the offsite storage.
Maybe you could do it with a big pipe between your backup location and your servers. But I bet that would cost a bundle in bandwidth.
Also did anyone notice that typo on UPS (maybe they were on drugs USP)! It took me a good minute to catch it.
"I'm just here to regulate funkyness." - James Gandolfini, as Winston in The Mexican
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.
If you don't want to repeat the past, stop living in it.
sPh
With the huge size of some databases, it would make more sense to connect to your offsite storage via fiber and store it there. There is no reason the backup disks need to be in the same room or building or state as the primary disks. Then you also solve the problem of reliably getting the data offsite in the first place. This is of course more expensive than renting a storage locker and driving a dat tape over to it every night, but I don't think Citibank is driving too many tapes around town. (just a guess)
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
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.
I looked at doing something similar (but on a smaller scale) for my home.. but the amount of power that a hard drive based storage system takes is amazing. In additional IDE hard drives arn't know for their reliability.. :P (I've had numerous IDE raids fail spectacularly to the point I won't do that again...)
I ended up going on ebay and getting a StorageTek 9714 "Media Library" with 2 DLT 4000 drives in it. It takes a maximum of 2A of power.. (I've measured it much lower then that when the tape drives arn't in use..) This sucker will store up to 2.4 TB ( 1.2 TB uncompressed) in the 60 available tape slots..
The electricity saves more then makes up for the cost of the tapes.. (Also I expect the tapes to last approx 5-10 years.. I wouldn't expect that with the hard drives.)
--Mark
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.
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.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
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.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
Oh PLEASE! I worked for, what was at the time, the 17th largest CC processor in the nation. Not so big, but lots of merchants. They bought a front-end (where your credit card terminals dial into), and built a backend settlement (so they didn't need FDR - who recently ROYALLY hosed everyone with a software update, including CHASE themselves. No, this software update was completely seperate from the SQL Slammer worm that took them down when it appeared.).
Complaince, usually done by the OTS (Office of Thrift Supervision), is NOT ISO 9000 type stuff. Financial companies are CHEAP. Never forget that. Whatever is the cheapest solution, is the one that is used.
As for tape backups - as an example: It took quite a bit of convincing to upgrade from the 4 drives that took two days to backup the whole network to a single Sont DLT drive. (Because $70/tape is a LOT of money)
There were no 'compliance' worries at all.
"I can't give you a brain, so I'll give you a diploma" - The Great Oz (blatently stolen sig)
A hard drive is sensitive to vibrations and has too many moving parts. The only reliable backup media is punch cards. Just don't store them near liquids.
Karma: The shiznight, mostly because I am the Drizzle.
Uh, if you have enough voltage differential to be creating microwave level effects in free space then data backup has ceased to be a concern.
In all likelihood the entire human race has also ceased to be a concern.
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.
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.
Offsite backups, whether tape or disk, present some pros and cons.
Pro: offsite is safer from local disaster effects.
Con: data restoration takes longer from further away.
Pro: high bandwidth connection makes moving data quick enough.
Con: high bandwidth connections are expensive
Con: high bandwidth connections are susceptible to disaster induced interruption
Overall, though, I like the random access provided by disk drives over linear searches of tapes. In case the network connection is broken to the backup site, you can easily load a couple of terabytes on cheap IDE drives into the back of your station wagon and bring them to any site you like and the effective BW will still be pretty darn good.
If you drive your station wagon across the continental U.S loaded with 3 TB of IDE drives in 3 days then you will be running faster than T1.
safer away from local disaster access time is high when locals need restoration big net pipe to far away but disaster that kills the network pipe ? maybe hard drives can be couriered back."Provided by the management for your protection."
Why do people in industries with strict uptime or reliability requirements always act holier-than-thou about the whole issue, as if their way is the only right way?
Not all companies need five 9's. Not all companies lose much money if data or systems are not available for a short time. In fact, I'd say it's the majority of companies that fall into that category.
Extreme reliability and availability are extremely expensive. For most companies, it's not worth it.
I agree with you, Large ATA RAID probably isn't for your industry, it's not right for everyone. It does work fine for lots of people though. I expect to see it cover much of the 5TB range of near-line backups in the next few years.
I've had enough abrasive sigs. Kittens are cute and fuzzy.