5 ms·

Well I've recently restored 150 LTO-2 tapes from 2002/2003 using a perfectly current LTO-4 drive, and I'm pretty sure you'd have a heck of a hard time successfu

by wazoox 13y ago

Well I've recently restored 150 LTO-2 tapes from 2002/2003 using a perfectly current LTO-4 drive, and I'm pretty sure you'd have a heck of a hard time successfully reading all of a bunch of 150 hard drives of the same vintage without losing a single file. Hard drives are much less reliable than tapes; hard drives aren't made to be stored on shelves; and when a hard drive fails, you most of the time lose most or all of its data, while a tape failure generally affects only one file (if it's a reasonably large file and you aren't using compression). As soon as your storage and archival needs are more than a few disk drives, do yourself a service and switch either to RDX or to tape. Storing basic HDD on shelves is a recipe for data loss. I know it because we sell backup solutions to people doing it and losing data all the time :)

bluedino 13y ago
>> Hard drives are much less reliable than tapes; hard drives aren't made to be stored on shelves; I can back this up. For some reason, someone decided to back things up to hard drives and even though they are stored in anti-static bags in a 600lb fire safe, when I remove the drives from 1 year ago to re-write with that months backup, I've had up to 1/2 the drives not spin back up. Ugh.
beagle3 13y ago
Disclaimer: my experience with tapes is dated. I used IBM tapes with a mainframe (System 390, library robot and all) until 1995, and then only used consumer level myself, but had witnessed the occasional horror story at a client's. > Well I've recently restored 150 LTO-2 tapes from 2002/2003 using a perfectly current LTO-4 drive, and I'm pretty sure you'd have a heck of a hard time successfully reading all of a bunch of 150 hard drives of the same vintage without losing a single file. That might be true. However, I have so far had perfect success with about 50 or so drives that I've restored from (across 10 years or so), and abysmal success with tapes (about 1/10 in the mainframe days would not restore). > Hard drives are much less reliable than tapes; hard drives aren't made to be stored on shelves; That's true, but neither are tapes. Hard drives are less tolerant to environmental conditions than tapes, they survive better when exposed to heat, and get damaged more quickly when exposed to cold (oils used to keep it running smooth tend to congeal irreversibly when exposed to cold for long). Also, at least in the past, even weak magnetic fields wreaked havoc on tapes, and even strong ones spared drives. > As soon as your storage and archival needs are more than a few disk drives, do yourself a service and switch either to RDX or to tape. Storing basic HDD on shelves is a recipe for data loss. I know it because we sell backup solutions to people doing it and losing data all the time :) In my current top-secret venture, I need to keep everything (~20TB/customer) randomly accessible for 3 years, and cold-store accessible or 7. So far, we just keep multiple copies (some online and some offline), and keep refershing to newer larger drives every couple of years. When I specced it 3 years ago, tapes were twice as expensive (I need a tape drive at every customer location + at least two at my office) and didn't properly address the random access aspect. But I keep re-evaluating. So far, the next step seems to be going to a BackBlaze style pod - which would also address the valid drive-fails-completely concern you raised. p.s., I find the "compressed" statistics really misleading. Every kind of backup software can compress - if I saw a hard drive manufacturer sell a ("2TB drive (1TB uncompressed)" I would consider it fraudulent, but that's the standard for tapes. For the record, my data is (as far as tape drives are concerned) not compressible at all -- think audio, video, jpegs, and other analog recordings. EDIT: p.p.s: Of course, don't keep hard drives on shelves. Nor tapes. Humidity and temperature need to be controlled, and the environment needs to be anti-static. For archival purposes, the 5400-RPM usb self-powered disks are a little slow, but keep very well, in my experience, with reasonable temp/humidity. EDIT2: (bad) memories are coming back. The biggest problem I recall with tapes in the mainframe days, were that some tapes (the daily and weekly backup sets) were continuously reused, to the point that mechanical wear and tear was a bigger problem than magnetic wear. And the even bigger problem was that you only found that out when trying to restore. One advantage of disks is that you keep reading them while writing them - wear is apparent much more quickly. If you're only doing archives and never rewrite tapes, that doesn't matter. If you keep reusing the same tapes/disks, it makes a huge difference in reliability.
- wazoox 13y ago
  Yes modern use case for tapes is archive, not backup. In fact, LTO-7 should be back-compatible from LTO-4 onwards to reflect this. Most people do backup disk-to-disk, with a remote copy on tape for instance.
beagle3 13y ago
> do yourself a service and switch either to RDX or to tape. Storing basic HDD on shelves is a recipe for data loss. What makes RDX (basically, an HDD encapsulated in a rubber cartridge) more reliable than e.g. an off-the-shelf rubber-USB-enclosed HDD? It's not like cartridge makers are making hard drives themselves - they source them from the same manufacturers as everyone else. All the complaints about HDDs for backup/archive apply to RDX, as far as I can tell. And at $100-$150/TB (and I can't even find cartridges bigger than 1.5TB for sale anywhere), it seems to combine with the worst price as well.
- wazoox 13y ago
  At least the RDX connector is made to withstand several thousand insertions (USB clearly can't). I suppose that the makers take some precaution to give some shelf durability to the drives within, too, but that's just a guess.
  - beagle3 13y ago
    I am unconvinced. If your archival media is going through thousands of insertions, then it's not archival - it's the most inefficient swap device ever. But I've connected/disconnected my laptop's USB mouse and keyboard a couple of thousands of time (several times a day over the last few years) and neither connector nor socket seem to be suffering. Furthermore, most of my cold store drives are of the self-powered USB 5400 RPM variety (getting a decent 30-40MB/sec on USB3) - if something breaks, I replace the $1 cable that connects drive to computer. Seriously, RDX seems like an awful choice - does someone here actually know differently?
    - hga 13y ago
      Yeah, it's not at all clear to me that USB connectors aren't worth "thousands" of insertion/removal cycles. They look very well thought out, plenty of contact area. Looks like it depends on the thickness of the gold contacts, per this supplier: http://www.globalconnectortechnology.com/usb-connectors/ http://www.globalconnectortechnology.com/usb-connectors/ USB2.0 Full Size: 1,500 mating cycles, gold flash plating. USB2.0 Mini: 5,000 mating cycles, 15µ” gold plating. USB2.0 Micro: 10,000 mating cycles, 30µ” gold plating. USB3.0 Full Size: 5,000 mating cycles, 30µ” gold plating. USB 3.0 Micro: 10,000 mating cycles, 30µ” gold plating. With an added comment: Why Micro types offer better durability? Accomplished by moving leaf-spring from the PCB receptacle to plug, the most-stressed part is now on the cable side of the connection. Inexpensive cable bears most wear instead of the µUSB device. Plus as you note, it's easy to make it a cheap replaceable part. Use a USB extension cable on the computer side and you won't be wearing that out (I've done that trick in times past).

by wazoox 13y ago

bluedino 13y ago

>> Hard drives are much less reliable than tapes; hard drives aren't made to be stored on shelves; I can back this up. For some reason, someone decided to back things up to hard drives and even though they are stored in anti-static bags in a 600lb fire safe, when I remove the drives from 1 year ago to re-write with that months backup, I've had up to 1/2 the drives not spin back up. Ugh.

beagle3 13y ago

Disclaimer: my experience with tapes is dated. I used IBM tapes with a mainframe (System 390, library robot and all) until 1995, and then only used consumer level myself, but had witnessed the occasional horror story at a client's. > Well I've recently restored 150 LTO-2 tapes from 2002/2003 using a perfectly current LTO-4 drive, and I'm pretty sure you'd have a heck of a hard time successfully reading all of a bunch of 150 hard drives of the same vintage without losing a single file. That might be true. However, I have so far had perfect success with about 50 or so drives that I've restored from (across 10 years or so), and abysmal success with tapes (about 1/10 in the mainframe days would not restore). > Hard drives are much less reliable than tapes; hard drives aren't made to be stored on shelves; That's true, but neither are tapes. Hard drives are less tolerant to environmental conditions than tapes, they survive better when exposed to heat, and get damaged more quickly when exposed to cold (oils used to keep it running smooth tend to congeal irreversibly when exposed to cold for long). Also, at least in the past, even weak magnetic fields wreaked havoc on tapes, and even strong ones spared drives. > As soon as your storage and archival needs are more than a few disk drives, do yourself a service and switch either to RDX or to tape. Storing basic HDD on shelves is a recipe for data loss. I know it because we sell backup solutions to people doing it and losing data all the time :) In my current top-secret venture, I need to keep everything (~20TB/customer) randomly accessible for 3 years, and cold-store accessible or 7. So far, we just keep multiple copies (some online and some offline), and keep refershing to newer larger drives every couple of years. When I specced it 3 years ago, tapes were twice as expensive (I need a tape drive at every customer location + at least two at my office) and didn't properly address the random access aspect. But I keep re-evaluating. So far, the next step seems to be going to a BackBlaze style pod - which would also address the valid drive-fails-completely concern you raised. p.s., I find the "compressed" statistics really misleading. Every kind of backup software can compress - if I saw a hard drive manufacturer sell a ("2TB drive (1TB uncompressed)" I would consider it fraudulent, but that's the standard for tapes. For the record, my data is (as far as tape drives are concerned) not compressible at all -- think audio, video, jpegs, and other analog recordings. EDIT: p.p.s: Of course, don't keep hard drives on shelves. Nor tapes. Humidity and temperature need to be controlled, and the environment needs to be anti-static. For archival purposes, the 5400-RPM usb self-powered disks are a little slow, but keep very well, in my experience, with reasonable temp/humidity. EDIT2: (bad) memories are coming back. The biggest problem I recall with tapes in the mainframe days, were that some tapes (the daily and weekly backup sets) were continuously reused, to the point that mechanical wear and tear was a bigger problem than magnetic wear. And the even bigger problem was that you only found that out when trying to restore. One advantage of disks is that you keep reading them while writing them - wear is apparent much more quickly. If you're only doing archives and never rewrite tapes, that doesn't matter. If you keep reusing the same tapes/disks, it makes a huge difference in reliability.

wazoox 13y ago
Yes modern use case for tapes is archive, not backup. In fact, LTO-7 should be back-compatible from LTO-4 onwards to reflect this. Most people do backup disk-to-disk, with a remote copy on tape for instance.

beagle3 13y ago

> do yourself a service and switch either to RDX or to tape. Storing basic HDD on shelves is a recipe for data loss. What makes RDX (basically, an HDD encapsulated in a rubber cartridge) more reliable than e.g. an off-the-shelf rubber-USB-enclosed HDD? It's not like cartridge makers are making hard drives themselves - they source them from the same manufacturers as everyone else. All the complaints about HDDs for backup/archive apply to RDX, as far as I can tell. And at $100-$150/TB (and I can't even find cartridges bigger than 1.5TB for sale anywhere), it seems to combine with the worst price as well.

wazoox 13y ago
At least the RDX connector is made to withstand several thousand insertions (USB clearly can't). I suppose that the makers take some precaution to give some shelf durability to the drives within, too, but that's just a guess.
- beagle3 13y ago
  I am unconvinced. If your archival media is going through thousands of insertions, then it's not archival - it's the most inefficient swap device ever. But I've connected/disconnected my laptop's USB mouse and keyboard a couple of thousands of time (several times a day over the last few years) and neither connector nor socket seem to be suffering. Furthermore, most of my cold store drives are of the self-powered USB 5400 RPM variety (getting a decent 30-40MB/sec on USB3) - if something breaks, I replace the $1 cable that connects drive to computer. Seriously, RDX seems like an awful choice - does someone here actually know differently?
  - hga 13y ago
    Yeah, it's not at all clear to me that USB connectors aren't worth "thousands" of insertion/removal cycles. They look very well thought out, plenty of contact area. Looks like it depends on the thickness of the gold contacts, per this supplier: http://www.globalconnectortechnology.com/usb-connectors/ http://www.globalconnectortechnology.com/usb-connectors/ USB2.0 Full Size: 1,500 mating cycles, gold flash plating. USB2.0 Mini: 5,000 mating cycles, 15µ” gold plating. USB2.0 Micro: 10,000 mating cycles, 30µ” gold plating. USB3.0 Full Size: 5,000 mating cycles, 30µ” gold plating. USB 3.0 Micro: 10,000 mating cycles, 30µ” gold plating. With an added comment: Why Micro types offer better durability? Accomplished by moving leaf-spring from the PCB receptacle to plug, the most-stressed part is now on the cable side of the connection. Inexpensive cable bears most wear instead of the µUSB device. Plus as you note, it's easy to make it a cheap replaceable part. Use a USB extension cable on the computer side and you won't be wearing that out (I've done that trick in times past).