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Ask Slashdot: Personal Tape Drive NAS?
New submitter hey_popey writes "I would like to piggyback on a previous Ask Slashdot question. Do you know of any realistic way to use a tape drive solution at home, not as a backup, but as a regular NAS? I would like, for example, to save the torrents of my Linux distributions on it, and at the same time, play the family videos on a computer. It would seem at a first glance that the transfer rates and capacity of Linear Tape-Open (1.5TB, 280MB/s in 2010) and the functionality of LTFS would allow me to do that, but I don't know the details, or whether this would be economically viable."
you're not thinking this through, are you? it's a tape-drive...
No. Just no.
you'd need a cache drive in front of it.
the mb/s is ok yes, but that's for linear read/write from the tape.
"While specifications vary somewhat between different drives, a typical LTO-3 drive will have a maximum rewind time of about 80 seconds and an average access time (from beginning of tape) of about 50 seconds.[21][dead link] Note that due to the serpentine writing, rewinding often takes less time than the maximum."
the tape is also only good for 260 full passes.
just buy a hd based nas, archive to tape if you really archive that much stuff. but load it on hd first for gods sake.
world was created 5 seconds before this post as it is.
Unless you stuff a large harddisk inbetween as cache, I don't see how you can make this perform anywhere near bearable.
Note that frequent write/delete cycles will fragment tape space like you wouldn't believe (perhaps a weekly tape reorganization job would be in order?).
I used to work on z/OS where using tape for normal storage isn't unheard of; typically files not accessed for a while are moved to a tape robot.
When trying accessing one of those files, it did so by writing the file back to harddisk for actual access.
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For playing a movie - maybe. For actually burning a torrent - fair enough... if that is the _only_ thing that happens.
The point is that multiple accesses is going to delay the drive by a huge amount. If you want to, say, copy that Linux iso to your NAS at the same time as someone is playing a movie, the tape drive is going to have to move between the locations of the two files, which is going to wreck the access times, as I stated. Torrents are worse: you're downloading from / uploading to a bunch of other computers, all wanting to read from or write to a different location in the file. Again, this means moving between locations and the resulting huge access times.
You may be able to alleviate the process by putting a SSD or HD as cache in between, but I'm not sure if there's off-the-shelf software to do that, and I'm not even sure if that's going to work comfortably. Besides, if you're going to put a SSD or HD in between, why not just use that?
The last point in particular is why you don't see HDD robots: all that handling would skyrocket the hard drives' failure rate.
"A *person* is smart. People are dumb, panicky, dangerous animals and you know it."
- 'K' in Men in Black.
I only live with my partner & there's many circumstances where I'm copying to/from my server while she's watching a video & vice versa. Then there's downloading a torrent on the server while both of us are accessing it. Even if it's one person, if you're watching a movie & even refresh the directory listing your movie would stop. This is probably the worst "Ask Slashdot" I've ever seen.
Written by someone with no grasp of technology & approved by someone with even less of a grasp on reality.
1) Fast
2) Cheap
3) Large capacity.
Pick two.
No sig today...
"Written by someone with no grasp of technology"
Your comment written by someone with no grasp of the history of technology. There's folks reading your words who remember reading and storing files from cassette tapes in the 1980s. Like me.
"approved by someone with even less of a grasp on reality"
Story approved by someone with an appreciation that the geekiest novel solutions to problems are things unimaginative people would never consider seriously until forced to, because everyone else is enthusing about how cool it is. Let your mind wander into crazy scenarios and impossible what-ifs. Or butt out. Because some people come to Slashdot for exactly this talk on just this topic of the way-out-there.
"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." - Andrew Tanenbaum, 1996, Computer Network
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"Written by someone with no grasp of technology"
Your comment written by someone with no grasp of the history of technology. There's folks reading your words who remember reading and storing files from cassette tapes in the 1980s. Like me.
I too used tape drives in the 80s, but my grass is not remotely brown enough and my glasses are not tinted nearly enough to begin to think of those as "the good old days" when thinking about storage solutions. I agree with the GP that this question was asked by someone that doesn't have any clue what the linear nature of a tape means and has never been stuck waiting on a restore of a file that happens to be at the opposite end of the tape than the current position.
I would agree with you about "novel solutions" if the question had instead been about how to use a disk and tape combination similar to RAM/swap and age out files with low access rates to tape while keeping the most used stuff on the faster disk or something else equally "out of the box". In this case it is just someone trying to use an exceptionally wrong tool for the wrong job and there is nothing novel about it (unless we are talking about the stupidity of it).
Also, Andrew was talking about transferring large amounts of data between sites in the days when the Internet was slow, HDDs weren't a good/stable transport method, and cross-site replication was expensive and limited in scope. He was not remotely referring to using tapes to solve an inherently random/multi access problem, so while it is still a funny quote it isn't relevant to the discussion at hand.
l
Of course, the practicalities might not be so great. If you want to share the torrent back with the community, then that's a problem. So is wanting to skip around in a video.
But I don't think the question is quite as insane as you make out.
Forgetting about or not thinking about the impracticalities is the insane part. I can hammer nails with my shoe but asking on a home improvement or shoe site the best way to reinforce my shoes so I can use them to build a tree house is pretty insane.
Well, there's spam egg sausage and spam, that's not got much spam in it.
"Never underestimate the bandwidth of a station wagon ..."
And never underestimate the latency either.
I still use tapes today, and I think they would be nice for home use since I can pick up LTO-3 tapes for about $15 a pop, and LTO-5 tapes for around $42 each.
However, if one thinks a tape can be a random access device, they need to think again. Tapes are great for making sure data is copied somewhere safely, and once the read/write switch is flipped, that the data stays safe.
My recommendation: Keep the tape drive for backups, but go with two mirrored drives, or some other RAID configuration (other than RAID 0) to minimize the impact of a HDD failure.
for the love of god, buy a regular NAS
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Back in the before time, I knew a guy who ran a BBS who came about a DAT drive by some method or another. I assume he stole it from work. Anywho, that was a lot of storage back then and he wanted to use it to store files for the BBS. What he came up with was a caching system where people tagged the files they wanted, the files would be copied from tape to temp storage on the hard drive, would be downloaded by the user, then deleted from the hard drive. I had a similar system for the CD-ROM changer on my multi-line BBS. If someone on line 3 wanted file from Disc_2 and someone on line 1 wanted a file from Disc_7, the poor thing would just thrash back and forth between discs until I added the caching system.
But it's just totally impractical today. I've got a 26tb array for my bulk storage. Even with hard drive prices still a bit inflated, it could be built for $2500 with nice drive cages. $3200 for 39tb using 3tb drives.
An LTO 5 library is going to run you $5000 for just the drive/library. You weren't going to stand there swapping tapes by hand, were you? Another $550ish to fill it with tapes. And that's only 1.5tb gigs per cartridge. (Native capacity is what you should be using for this type of data.) 16*1.5=24tb online for around $5500. Nevermind the cost of the caching system that would be needed just to make it work in even the most crude manner with a minimum of 5 minutes between initial request and the file being available for use. More than double if it spans tapes.
So roughly double the cost for a similar amount of storage with horrendous access times. Sounds like a plan. You should totally do it and report back.
I still use tapes today, and I think they would be nice for home use since I can pick up LTO-3 tapes for about $15 a pop, and LTO-5 tapes for around $42 each.
Not really home user price. LTO-3 is 400GB, LTO-5 is 1.5TB. At that sort of capacity, a home user is unlikely to need more than a handful of tapes. With LTO-5, three tapes would be enough for most home users with fairly aggressive backup strategy: two off-site, one being rewritten. If you're only buying three tapes, the cost of the drives becomes very important. The cheapest LTO-5 drives I can find cost over $1,000. At that price, you may as well just buy three 1.5TB hard drives and save the money. Tape is only really cost effective for situations where you have a lot of tapes.
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Yes. Enterprise backup with bucketloads of tapes. For Joe Home User, a couple of 2TB drives in enclosures would be very much cheaper, just as fast/faster, and about as easy to take offsite (which in my experience, never happens with home users).