Hard Drives Instead of Tapes? 484
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."
Far more practical (Score:5, Interesting)
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.
Compliance (Score:2, Interesting)
uh huh (Score:2, Interesting)
So, I come in, hit the systems with a hammer, and you're done. A virus wipes you out. A malicous hacker, a stupid user, kernel oops that fucks up the filesystem, something. No tapes to go back to. Not to mention that old data that isn't being used can be archived off to tape, which may end up costing less in the long run that more and more hard drives - hard drives use power, remember?
I never understand how you can trust you data to ONLY be on media that is tied to the mechanism. If the mechanism fails catastrophically, you're screwed. Tape separates the media from the mechanism, so a mechanism failure doesn't make your media worthless. Hard drives break eventually, tape is usually good for a number of years, (DLT, AIT, LTO, etc...)
Just a thought, anyway...
-E
Re:Sound fine, but... (Score:3, Interesting)
Tape will be with us for a while yet... (Score:5, Interesting)
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.
Optical isn't necessarily immune to EMP (Score:3, Interesting)
Re:Offsite? (Score:5, Interesting)
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.
Re:Sound fine, but... (Score:2, Interesting)
But wait there's more. Those mag tape cartriges have a transfer rate of about 10 MB/sec. With hard drives, your backups will take a fraction of the time they took under the old system. That leaves plenty of extra time to pack the drives up extra securely. You may even be tempted to do extra backups to send copies to multipls off-site locations!
Double plus good!
Re:Offsite? (Score:3, Interesting)
Re:Tape technology not keeping pace... (Score:3, Interesting)
Escelade 4 port IDE RAID card: around 200 bucks
200 Gig Drives X 5: say 249 each, = 1245
Total Cost: 1945
And thats 1000 GB of un-raided space, so will end up being more than 600 GB raid 5.
Re:Far more practical (Score:5, Interesting)
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 (Score:5, Interesting)
Re:Sound fine, but... (Score:2, Interesting)
Tape is Dead. Long Live Tape! (Score:2, Interesting)
The article mentions one major drawback, the inability to do offsite storage. You could work something out with offsite mirroring, but bandwidth costs at 70TB would get excessive. Not to mention needing the same hardware setup on the other end.
The other major advantage that tape has over disk is the archive ability. Once you write a tape, that data is static. I can have it sit in a slot in the library for a long time. Since this system is only designed for 5 years, archive is not a big deal, but a lot of industries it is huge. The ability to alter data on a disk drive seamlessly is a lot easier than to do on a tape.
The person who mentioned the shock/vibe values for a disk drive VS a tape cartridge: #1 I have dropped PLENTY of cartridges, and have only has one chip a corner. That chip did not affect my ability to use the tape further. Additionally, if the housing is destroyed, the process to spool off the tape, and splice it onto a different tape is not that difficult. I would not loose the data permanently. If there is a major mechanical failure inside a disk drive, getting the data off the platters is a lot harder.
I would be interested in seeing numbers for throughput of the system, power consumption, backup window lengths, average restore time. Some of these might stack up favorably to tape, others might not.
The comment on moving to optical as a backup medium - maybe someday, but for now the space needed/time to backup to optical does nto compare well with tape. A DVD of 4.5 GB VS a tape of 100GB (Currently available, yes I know blue lasers will improve that)
As for a robot failure, worst-case scenario, you put the tape in the drive manually. Realistically, at least at our company, we have solved this problem for our customers by providing the ability to easily replace components. This can happen either with a field engineer, or even the customer themselves. Generally all you need is a Phillips screwdriver, 20 minutes max, and the ability to follow instructions.
Again, I'm not in the sales department, so I can't quote costs, but a 435K total cost for 70TB is not that cheap. With tape systems, a lot of the cost depends on how fast the backups need to occur in. I could build out a 70 TB system with 1 drive, a SCSI connection and a huge wall of tapes relatively cheaply. As you add more drives, use fibre or gigabit Ethernet interfaces, etc costs go up, but access times go down. Cost can also be brought down by not going with the 500 lb gorilla of the field - StorageTek.
Yes disk is growing, but generally it does not replace tape, it only pushes it back a layer. This won't change for a while.
Re:Far more practical (Score:3, Interesting)
Re:Far more practical (Score:2, Interesting)
Re:Tape technology not keeping pace... (Score:1, Interesting)
The drives just keep getting more expansive. It's hard to budget for these kind of things without making people laugh. And my drives are always less reliable than the disk drives. Only 1/2 of my DLT7000 drives still work.
Re:Sound fine, but... (Score:3, Interesting)
Re:Far more practical (Score:3, Interesting)
And if you're really paranoid, each one has it's own power source, etc, etc, etc.
I can't believe I got a Score of 5 on that post though. heh.
-Alex
Re:Far more practical (Score:2, Interesting)
Re:Far more practical (Score:5, Interesting)
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
Re:Help me understand... (Score:3, Interesting)
First, I should note that I do consider sanity checks and cost/benefit analysis when making backup/recovery plans. So I agree with many of these comments. BUT...
(1) Disasters happen more often than people expect. And they can happen to you, not just the other guy. Wildpackets almost went out of business [eweek.com] as a result of underestimating that.
(2) Being out of business anyway - well - that's a discussion I had with the owner of one small company. I pointed out to him that one of his core values was loyalty to his employees. In the event of a big disaster, he and his family would collect the insurance check and sell the site, but his (former) employees' mortgage payments would continue. He got the point and agreed to improve disaster recovery plans.
(3) "Both of our sites will never get hit at the same time". I had a friend in charge of DR for a large company who analyzed 10 years of data center disasters and came to the same conclusion. He put the backup right down the street from the primary. Ever hear of the Great Chicago Flood [uic.edu]? Luckily for my friend he was working at another company when both his primary and backup were taken out by that event!
That's my 0.02 anyway.
sPh
Re:Let's see... (Score:1, Interesting)
Devil's advocate for a second: if you're going to do this, you put loads of hot spares into that array. Maybe 20% of your drives are hot spares. Then, of course, your RAID system will automatically fail over to hot spares in the event of a drive's failure. (If your RAID system doesn't do that, there's no sense in worrying about the safety of your data, because you're doomed.) Naturally, you'd also maintain a big stack of, say, 50 replacement drives somewhere.
So what you do is check the RAID array once every day or so. If, say, 3/4 of your hot spares are in use, then only 5% of your online drives are available as hot spares. At that point, which hopefully only happens every few months, you make a day of it and start replacing hard drive after hard drive. You take your big heap of 15 or 20 failed hard drives and mail them back for warranty repair all at once, in one big box. Hopefully the paperwork isn't too hard because probably you're on a first-name basis with the warranty department. :-)
This seems like a good idea until I think about what the RAID system is going to do when you try to replace 15 failed hard drives at once. It will have quite a time migrating all the data over. The power drain and heat generated from this activity may be more than the hardware can bear. It is also a scenario that the manufacturer's testing department is unlikely to have considered!
Re:Far more practical (Score:3, Interesting)
The perfect solution to backups would be notebook SATA disks, which should hopefully appear soon. Hotpluggable, no bulkier than an LTO or DLT tape, screaming fast compared to LTO and DLT, and very hard to damage when powered down. Capacities are about the same. Unlike tapes, I can rescue data off of a disk without needing an expensive and fragile drive.
Re:Far more practical (Score:2, Interesting)
Drag & drop backups that are fast and brainless. And the hand rolled system I built was cheaper than tape gear big enough and fast enough to do the same job.
It also does not need exotic software, at least in my case since I just use cron and a set of rsync scripts.
Easy, fast and getting cheaper every day. So I consider this to be non-news and sort of obvious and I am suprised more people are not doing it, other than they may have too much already invested in tape solutions to ever turn back.
It is not the be all end all. For example if you want fast disaster recovery you may want something else. ( But I'm not sure that keeping a synced copy of your OS partitions on a spare HD is a terrible idea.) For the places that this makes sense I can tell you its great.
FWIW