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Author Topic: What is safer for data -- a hard disk or a blue ray disc?  (Read 5253 times)

mouser

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What is safer for data -- a hard disk or a blue ray disc?
« on: July 07, 2013, 09:12:28 PM »
Say I want to archive a couple hundred gigabytes of data -- would i be better of burning it to a writable blu-ray disc or copying it to a hard drive placed on a shelf for long term storage?

I think the obvious answer, for important data, is probably: both.

But the question remains -- what would be the best media for storing terrabytes of data long term?

superboyac

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #1 on: July 07, 2013, 11:31:46 PM »
I would also be terribly interested in this.

I don't know how much blu ray discs are anymore, but if they are cheap, that's not a bad option, what is it 50GB per disc?

I'm a hard drive guy though.  I use file synchronization and back up the files in 2-3 separate drives.  I'm also trying to build a bigger tower or rack to hold up to 20 drives and really automate the process even more.  I think hard drives are the way to go for massive amounts of data, like terabytes you mentioned.  One 4TB drive or 80 blu ray discs?  In the early 2000s, I was backing stuff up regularly on cdr's, and i just don't have that kind of energy or desire anymore.

What is disturbing to me and complicates matters is that hard drives are becoming less in demand it seems since everyone has moved to mobile devices.  So they are not as cheap as we are used to seeing anymore, nor are they increasing in size as quickly as they used to.  Seems like 4TB is the limit currently and has been for a while.  So I'm not sure what the future of hard drives are.  I'd still prefer a hard drive over a SSD, but I'll wait until they catch up in capacity (probably a long time).

The other related thing to keep an eye out are the transfer protocols (esata, usb 3.0, thunderbolt).  None of them really caught on to any degree.  I went on a massive search to find a pcie card or something to add multiple usb 3.0 ports to my computer, and there are hardly any that offer more than one or two connections.  There's nothing for theunderbolt.  There's not much for esata either.  Some of those weird chinese sites like alibaba have some interesting stuff, but they aren't terribly reliable.

I'm curious if there are any side effects for hard drives that are sitting on a shelf for a long time (years).  Should you plug them in once in a while to keep them happy or anything like that?

I sometimes have disturbing formatting issues that come up with these large drives that i plug in and out of computers.  Let's say i put a bunch of data on a huge 4tb drive.  Then i take it out.  Later, I use it with an enclosure and a usb 3.0 connection.  Then I do the same with an esata.  Then i stick it into another computer.  Sometimes, while doing this, Windows will say the drive is unreadable or something, or that it has to be formatted, or that it is corrupted.  And I have a feeling that it is due to all the different cables/protocols the drive is being accessed with, but I can't really confirm it for sure.  But when the message comes up and the drive is a critical step in your backing up process, it's pretty scary.  I hate that feeling.  I'm always keeping a close eye on developments with hard drives, esata/sata, usb 3.0, thunderbolt/lightpeak, enclosures, etc.

SKA

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #2 on: July 08, 2013, 06:09:12 AM »
BDs have chemical/polymer coating which can degrade with exposure to moisture etc.
Current 7200rpm/10K rpm hard disks don't have such issues but could be affected by strong magnetic forces/radiation.
I choose hard disks(enterprise version better than consumer versions) over Blueray disks. Not keen on RAID in any form.

Ska

tomos

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #3 on: July 08, 2013, 07:14:24 AM »
I wonder how the "M-Disk" is getting on?
new DVD "M-Disc" perfect for archive material (dc link)


edit/ scratch that - they still dont have blue ray discs...
http://www.mdisc.com/what-is-mdisc/
Tom

mwb1100

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #4 on: July 08, 2013, 01:00:20 PM »
I'm curious if there are any side effects for hard drives that are sitting on a shelf for a long time (years).  Should you plug them in once in a while to keep them happy or anything like that?

Since hard discs are mechanical devices with bearings for the platters to spin on, I'd expect that it would be a good idea to periodically spin them up to help make sure the bearing doesn't seize.

Long ago I had a 20MB hard disc (yes, megabytes; this was a very long time ago) that had a 'stiction' problem (Stictionw). This wasn't a problem with the bearings, but of the heads sticking to the platters when the device wasn't in operation for a while.  When powered up, the platters wouldn't spin because there was enough friction between the heads and the platters they were resting on before spinning up.  I managed to get my data off the drive by taking the top off and giving the platters a little nudge near the hub.

I don't know if today's hard discs are susceptible to that same problem, but anything with moving parts may find it difficult to get going again after being unused for a long period.

So if you decide on using hard discs, I'd also work on a media rotation plan - that might be a good idea regardless of the medium you choose.  It might also be wise to use something like the parchive format (Parchivew) so that you have a chance for recovery if some pieces of the data were corrupted/lost. (Disclaimer - I haven't used anything like the parchive format myself, so I don't know how usable and effective it is in practice).

CWuestefeld

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #5 on: July 08, 2013, 01:37:52 PM »
I've *read* lots of stuff about limited lifespans of DVD-R (and by extension, I guess) BD-R discs. But in practice, I occasionally read archives from 10 years ago without problems.

I prefer to do this via hard drive for really big amounts of data, because chopping up the archives, and figuring out what's on what disc, is a big pain. Actually, I just bought a cheap large drive for an additional backup of my photos and documents, when I move in a couple of months - I'm worried about what a hot moving truck will do to hard drives, so I'll carry this one with the real crucial stuff with me.

Continuing to argue with myself... setting aside the life of optical bits versus magnetic bits, there's also long-term questions of form factor. My bet is that you'll have a device that can read optical discs longer into the future than you'll have a device that accepts the kind of interface on your hard disk. I mean, CDs and DVDs have been around quite a long time, and readers are ubiquitous. But if you had your data on an IDE or (some kinds of) SCSI hard drive, and you'd have a much more difficult job trying to find a reader.

MWB1100 reference parchives (like PAR2) above, which is one way to add redundancy so that small failures are recoverable. Another approach, if you're using optical discs, is to use DVDisaster. This is essentially the same thing as PAR2, but it's hidden outside the file system for transparency, and operates against the entirety of the disc image.


Shades

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #6 on: July 09, 2013, 10:49:24 PM »
Decent quality, slow burned disc´s that are kept in their box in a dry, dark place at a constant temperature do last a long time. Here in Paraguay disc´s are not that great, mainly because of the shitty quality of the players. Getting a disc to work here is a crap shoot. I have 8 DVD burners here and none of the disc I have burned over time work at any given time in any given player.

This is so ff-ing frustrating that I have abandoned this whole tech...until I could lay my hands on a DVD burner that came from the Netherlands. With that drive all discs work all the time. Depending on where you are, and the quality of the reader you can get, disc´s could be an option.

Maybe it would even be a good idea to flip hard disc´s that are in storage every 6 months or so, just to be sure gravity has not too much effect on the (grease of the) bearrings. But in any case, hard disc´s would be my preferred storage medium.

Support for SCSI drives is less of a problem than for IDE drives, It is often easier to get a separate SCSI controller, while getting a separate IDE controllers is a lot harder to get.  As onboard IDE controllers were adequate in most cases, the need for separate IDE controllers is/was practically eliminated.

I only know about soundcards, back when Windows 3.11 was king, that came with a separate IDE controller, which were only useable if you had the IRQ´s to spare...on your motherboard with ISA ports! SCSI controllers at least progressed... ;D

zenzai

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #7 on: July 12, 2013, 05:18:44 AM »
I would also be terribly interested in this.

I don't know how much blu ray discs are anymore, but if they are cheap, that's not a bad option, what is it 50GB per disc?

Dual Layer (DL) disks can hold 50 GB. But I'm a bit sceptical about Blu-Ray disks, because of the high data capacity. This means much more data per square inch, which requires a much higher precision both when manufacturing the disc as well as in the mechanics of the drives. With DL discs an even higher precision is required. I've just bought my first Blu-Ray drive though so I don't have much practical experience with them yet. One thing I experienced though is that the Blu-Ray drive was capable of reading some DVD discs without any problems which my DVD drives had problems reading (some sectors were reported unreadable).

The problem is the same with HDDs. A tiny error in the data layer on a low capacity disk may only affect part of a single bit, so that bit is still readable. On a high capacity disk (say 20 times higher capacity) the same error may affect several bits and make them unreadable. I've also noticed a lot more weak sectors (sectors that aren't so bad that they're unreadable and needs to be reallocated, but bad enough to take a long time to read) on high capacity disks. I bought two identical 2 TB disks last year myself, the one is OK but the other is extremely slow when it comes to read/write operations. Trying to figure out what was wrong I tried replacing cables, switch SATA ports etc., but nothing helped. Eventually I bought Hard Disk Sentinel and tested the drive, which revealed a lot of weak sectors. I haven't experienced that with disks with lover capacity.

Quote
I'm a hard drive guy though.  I use file synchronization and back up the files in 2-3 separate drives.  I'm also trying to build a bigger tower or rack to hold up to 20 drives and really automate the process even more.  I think hard drives are the way to go for massive amounts of data, like terabytes you mentioned.  One 4TB drive or 80 blu ray discs?  In the early 2000s, I was backing stuff up regularly on cdr's, and i just don't have that kind of energy or desire anymore.

I prefer HDDs too, much easier to work with, and also safer in general IMO, at least if you back up on at least two separate drives. I also use online/cloud backup as an extra precaution.

I used to use DVDs, but then I always made 3 copies on different DVD brands, as some brands (or batches/types of the same brand) deteriorate faster than others. I recently transfered about 100 DVDs to HDD, they were several years old and practically all DVDs of a certain brand (Hyundai) were totally unreadably while the other brands I'd used were fine.

Quote
What is disturbing to me and complicates matters is that hard drives are becoming less in demand it seems since everyone has moved to mobile devices.  So they are not as cheap as we are used to seeing anymore, nor are they increasing in size as quickly as they used to.  Seems like 4TB is the limit currently and has been for a while.  So I'm not sure what the future of hard drives are.  I'd still prefer a hard drive over a SSD, but I'll wait until they catch up in capacity (probably a long time).

They're also coming close to the data layer capacity that's possible for HDDs. The more data per square inch, the more mechanical precision is required on all levels as well. That you actually can store 4 TB on a drive these days, and still maintain reliability, is impressive, IMO. It takes an incredible mechanical precision to be be able to do that, not to mention the speed the drives are operating at.  

Quote
I'm curious if there are any side effects for hard drives that are sitting on a shelf for a long time (years).  Should you plug them in once in a while to keep them happy or anything like that?

I've never had any problems with drives that have been stored for a long time (3 years or more). Just tried to plug a 13 year old Seagate drive which I haven't used for years into a docking station, no problems. Seagate has stated that the fluid bearings that has been the standard for about 10 years now could practically "run forever" if the rest of the mechanics didn't wear out, how they react to long time inactivity may be a different matter though. But 3 years or so don't seem to be a problem in general.

Quote
I sometimes have disturbing formatting issues that come up with these large drives that i plug in and out of computers.  Let's say i put a bunch of data on a huge 4tb drive.  Then i take it out.  Later, I use it with an enclosure and a usb 3.0 connection.  Then I do the same with an esata.  Then i stick it into another computer.  Sometimes, while doing this, Windows will say the drive is unreadable or something, or that it has to be formatted, or that it is corrupted.  And I have a feeling that it is due to all the different cables/protocols the drive is being accessed with, but I can't really confirm it for sure.  But when the message comes up and the drive is a critical step in your backing up process, it's pretty scary.  I hate that feeling.  I'm always keeping a close eye on developments with hard drives, esata/sata, usb 3.0, thunderbolt/lightpeak, enclosures, etc.

That problem can be caused by not dismounting (safe removal) the drive correctly when using an USB or eSATA connection (the write back cache is not written to the disk before it's shut down, as it should, which may cause data loss or corruption). Some eSATA drives like WD MyBook can not be dismounted when first mounted (Windows does not show the option), others can. When first plugged in you have to keep them running until you shut down the PC.  

« Last Edit: July 14, 2013, 11:32:27 AM by zenzai »

mouser

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #8 on: July 12, 2013, 05:34:15 AM »
Nice post, zenzai  :up:

Crush

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #9 on: July 12, 2013, 05:37:24 AM »
I´m waiting for this a very long time now: Over 10 years the technology of the Hyper CD is available, but not official for standard users. The first working prototype was shown 1999.

    Capacity: 1 PB (with possibility of extension up to 100 EB)   100 Exabyte = 100.000 Petabyte = 100.000.000 Terabyte = 100.000.000.000 Gigabyte!!!  ;)
    (that´s multiple times more than 64 bit processors can theoretically adress)
    Medium transfer rate: 300 Mbit/s (may be more) ... today it can be surely much faster
    Hard drive dimensions: 80 x 150 x 300 mm (with some optimizing it should be possible to shrink this a bit)
    Disk dimensions: 1.2 mm ø 120 mm
    Temperature resistance: up to 550°C (ok for my needs  :))
    High reliability
    Maximum usage period: 5,000 years - all over 100 years is enough in my opinion

With this you can save the complete computer & internet history up to the next 50 years without problems on one disc, but I think this is the reason why we won´t get this storage device during the next 50 years.

:Thmbsup:

Meanwhile until it´s available I personally changed to HD storage this year - I´m still copying all my discs (self burned & originals) as mds files there.
« Last Edit: July 12, 2013, 06:00:03 AM by Crush »

zenzai

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #10 on: July 12, 2013, 05:56:00 AM »
Continuing to argue with myself... setting aside the life of optical bits versus magnetic bits, there's also long-term questions of form factor. My bet is that you'll have a device that can read optical discs longer into the future than you'll have a device that accepts the kind of interface on your hard disk. I mean, CDs and DVDs have been around quite a long time, and readers are ubiquitous. But if you had your data on an IDE or (some kinds of) SCSI hard drive, and you'd have a much more difficult job trying to find a reader.

You usually have quite a long time to transfer your data to other formats though. You can still buy PATA (IDE) controllers like Promise Ultra 133 TX2, as well as docking stations for PATA drives. And WD (and possibly other manufacturers as well) are still producing a few PATA drives.

zenzai

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #11 on: July 12, 2013, 05:57:06 AM »
Nice post, zenzai  :up:

Thanks! Hope someone finds it useful...  ;)

longrun

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #12 on: July 13, 2013, 12:28:03 PM »
Quote
I sometimes have disturbing formatting issues that come up with these large drives that i plug in and out of computers.  Let's say i put a bunch of data on a huge 4tb drive.  Then i take it out.  Later, I use it with an enclosure and a usb 3.0 connection.  Then I do the same with an esata.  Then i stick it into another computer.  Sometimes, while doing this, Windows will say the drive is unreadable or something, or that it has to be formatted

After having the unformatted disc problem with a HD used for backups I discovered Partition Find & Mount, mentioned elsewhere on the forum. What a relief to see my missing partition reappear!

I agree with zenzai about the cause, but now I don't even trust Safe Removal as I've been pretty careful. Whenever possible I turn off my notebook and disable write-back caching.

zenzai

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #13 on: July 13, 2013, 12:51:53 PM »
I agree with zenzai about the cause, but now I don't even trust Safe Removal as I've been pretty careful. Whenever possible I turn off my notebook and disable write-back caching.

I'm using Zentimo to handle my USB connections, I don't know if it is safer when it comes to Safe Removal but I've never had any problems with my disks in this respect.

superboyac

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #14 on: July 14, 2013, 01:08:49 AM »
I agree with zenzai about the cause, but now I don't even trust Safe Removal as I've been pretty careful. Whenever possible I turn off my notebook and disable write-back caching.

I'm using Zentimo to handle my USB connections, I don't know if it is safer when it comes to Safe Removal but I've never had any problems with my disks in this respect.
i love zentimo.  for the simple reason that the gui is very easy and clear about what you are stopping/removing.  not the confusing presentation that comes with windows, good grief.  every time i use the default windows one, i always go through a moment where i'm like "This SEEMS to be the right drive I'm removing, but I'm not exactly sure.  oh well, here goes!"

superboyac

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #15 on: July 14, 2013, 01:11:42 AM »
That problem can be caused by not dismounting (safe removal) the drive correctly when using an USB or eSATA connection (the write back cache is not written to the disk before it's shut down, as it should, which may cause data loss or corruption). Some eSATA drives like WD MyBook can not be dismounted when first mounted (Windows does not show the option), others can. When first plugged in you have to keep them running until you shut down the PC.
That's something I need to remember.  You never want a little impatient urge to ruin a 4TB drive.  :(

Vurbal

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Re: What is safer for data -- a hard disk or a blue ray disc?
« Reply #16 on: July 14, 2013, 11:00:18 AM »
I would never trust important data to long term storage on any burned optical disc. The problem is that nobody really knows how quickly the organic dye used will last. We're only now getting an understanding of how quickly the dye on DVD recordables degrades. For BD it's still an almost complete unknown. The manufacturers make claims but those are theoretical and as we're finding out with DVD they should be taken with a huge grain of salt.

If you're going to go that direction my recommendation would be to find 2 different types of disc that use different dyes and make duplicate copies of everything. Of course you would also probably need to test at least a couple samples of each every 6 months or so if you want to be safe.

As I understand it hard drives have a slightly different problem in theory. Supposedly it's not good for the lubricant used for the spindles if they don't spin up regularly. Having said that, I've had hard drives sit for a couple years and then go back into full time use without any problem. I don't think I've ever put one away that was working and then have it fail when I took it back out.
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« Last Edit: July 14, 2013, 06:15:37 PM by Vurbal, Reason: People aren\'t mind readers »