Sign in with
Sign up | Sign in
Your question
Solved

Optical vs. external HD for back-up

Tags:
  • Storage
  • Product
Last response: in Storage
Share
March 30, 2011 7:20:24 PM

I hope this is the right area for this question.

I have two 500GB external drives with about 700GB of video and music between them. I've gotten worried about losing one of them (I fly a lot with work), or having one of them die on me, and losing all of it so I'm going to back them up. I was going to buy a blue-ray burner and do optical backups but that's still 30-40 disks. Then I found out that the store near me has a 1TB external drive for less than the blue-ray burner.

How long can i expect the data on a HD to last without corruption? I've had DVD's die on me a few years after I burned them so the difference might not be that big.

So has anybody else done this before?


Charles

More about : optical external back

Best solution

a c 415 G Storage
March 30, 2011 7:30:42 PM

The problem with backups on ANY media (including hard drives, DVDs, BDs, tape, etc) is that NO media is 100% safe. The key to making sure your data is protected is to have copies of it in multiple places.

I use hard drives for backups and archives, but I back everything up twice using two different drives. With bare 2TB drives selling for about $80 these days, it's more economical and far more convenient to do this that to use optical discs. I use an external bare drive dock so that I can buy the cheap bare drives without having to pay extra for the enclosure.

What I like about hard drives is that I can run periodic checks of the drives. I use a checksumming utility to verify that every bit of data can still be read correctly. That way I can pop a drive into the dock and let it hum away in the background checking the files without having to manually load discs one after another. If anything goes wrong with one drive I'll know - then I can replace the bad drive and recover the files from the other drive. This avoids the fatal flaw in optical disc backups - people never bother to check all of them them to ensure that they're still readable because of the manual work involved.
Share
a b G Storage
March 30, 2011 7:35:29 PM

HDD's fail too, typically if a HDD is going to fail early its within the first month or two depending on usage. If the drive doesnt fail it can last years and years, and unless you delete the data or the drive fails all your data will still be there like it was orgionally.

Depending on how valuable they are to you I would recommend buying adn External HDD with 2x1TB drives in RAID 1, so if one drive fails all the data is duplicated on the other. Since you have such a large collection of HD video you would want to get a External HDD with USB 3.0 or eSATA, which will make file transfers much faster.
m
0
l
Related resources
a c 415 G Storage
March 30, 2011 9:06:01 PM

Snipergod87 said:
Depending on how valuable they are to you I would recommend buying adn External HDD with 2x1TB drives in RAID 1, so if one drive fails all the data is duplicated on the other.
IMHO you're better off with two copies of your data on two separate external hard drives rather than on two hard drives in the same RAID-1 enclosure. The RAID-1 data is toast if you drop it, if it's subject to some sort of power hit, if it's stolen, etc. etc. Separate drives can be stored separately (you can even keep one offsite) to virtually eliminate any possibility of data loss from a common-mode risk.

It's important to remember that drive failure is not the only way you can loose data...
m
0
l
a b G Storage
March 31, 2011 12:36:28 AM

halomon said:

How long can i expect the data on a HD to last without corruption? I've had DVD's die on me a few years after I burned them so the difference might not be that big.



Here is an article which talks about magnetic failure over time. If you make a backup of something important such as home movies or pictures and take that HDD and put it on the shelf it may fail unless 'plugged in' sometimes. Can't corroborate this story but here is his summary 'stolen' from this article:

Danger! The 'facts' you are about to read are likely bogus. Please enjoy using them as food for thought and continued discussion.

http://www.larryjordan.biz/articles/lj_hard_disk_warnin...

When I read your statement (above) I assumed this is what you were asking about and I have wondered about this before too.


Executive Summary

Magnetic signals recorded on a hard disk are designed to be refreshed periodically. If your hard disks stay on, this happens automatically. However, if you store your projects to a removable hard drive, then store that hard drive on a shelf, unattached to a computer, those magnetic signals will fade over time... essentially, evaporating.

According to what I've been told, the life-span of a magnetic signal on a hard disk is between a year and a year and a half. The issue is complex, as you'll see, but this is a MUCH shorter shelf-life than I was expecting.

The way to keep the files on your hard disks safe is to connect the hard drive to your computer every six months or so and, ideally, copy all the files from one drive to another. Failing that, use a program like Micromat's TechTool Pro, or ProSoft's Drive Genius, to do a complete scan of your hard drive. Doing so will replenish any magnetic signals that are starting to fade.
m
0
l
a c 415 G Storage
March 31, 2011 1:24:47 AM

adampower said:
Here is an article which talks about magnetic failure over time.
I don't know who this "Larry Jordan" fellow is or what his credentials are, but that article is, frankly, BS. Reading the data from a hard drive does nothing to "refresh" it. The only thing that "refreshes" the data on the drive is re-writing it, and the only way to do that is basically to back the whole drive up to external media and then restore everything. And frankly, even that doesn't overwrite the sector preambles which are used to locate the data - those are written at the factory and never, EVER "refreshed".

The only instance in which data on a magnetic disc could be said to be "refreshed" upon reading is if errors are detected when the data is read. In that case the controller will rewrite the data into a "spare" sector and update its mapping tables to indicate that the failing sector has been replaced by the new one. From that point on all reads and writes to the affected sector will be redirected to the spare sector instead. But that occurs only for errors, and there are nowhere near enough spare sectors to "refresh" all the data on a drive.

And the "data only lasts 1 to 1.5 years" claim is also completely false. As a datacenter administrator I've had hard drives in continuous service for as much as a decade or more with no issues.

The idea that reading the data "refreshes" it is completely bogus, but there is a grain of truth in there - it IS a good idea to read all the files on your drive from time to time so that you can check to see if errors were reported when any of the data was read. That way, if there's any unreadable data on your drive you'll be able to recover it from your backups before it's too late. Fortunately the very act of backing the disk up does this for you - another reason why regular backups are a good idea. Just remember to check to see if there were any errors reported when the backup ran.

Now it could be that this article is using "refresh" as a kind of layman's oversimplification of what I described above - but IMHO it falls short because it just says "read all the data" and mentions nothing about "checking for errors", which would be the real reason you'd do this.
m
0
l
a b G Storage
March 31, 2011 1:50:58 AM

sminlal said:
As a datacenter administrator I've had hard drives in continuous service for as much as a decade or more with no issues.


Thanks sminlal. I wondered about this article myself and that's why I put the disclaimer at the top. However I have often wondered what would happen if one were to put the drive on the shelf for an extended period. Similar to putting your super 8 family videos on the shelf. Your drives were writing and rewriting continuously for a decade....

However, I will edit the original message with a LARGER disclaimer as I don't know this Larry character at all but have read plenty of your expert posts.
m
0
l
a b G Storage
March 31, 2011 4:17:03 PM

Quote:
And the "data only lasts 1 to 1.5 years" claim is also completely false. As a datacenter administrator I've had hard drives in continuous service for as much as a decade or more with no issues.

Made me laugh, who is this Larry guy? Did he only buy Maxtor hard drives? Our server room has some 15k 18GB hard drives that have been there running 24/7 for god knows how long. Even my desktops drives have been kicking for about 3 years, some of my laptops longer than 5..

But I do want to point out to the OP that DVD and CD media can cause be damaged by sunlight, humidity, time and the quality of the media.
m
0
l
April 1, 2011 8:12:56 PM

Best answer selected by halomon.
m
0
l
April 1, 2011 8:15:36 PM

I wish i could give best answer to more than one person but can't. sminlal got it because I went with his plan. Great idea. But thanks to Snipergod87 and adampower for you help as well.

Charles

m
0
l
May 31, 2011 8:09:34 AM

sminlal said:

What I like about hard drives is that I can run periodic checks of the drives. I use a checksumming utility to verify that every bit of data can still be read correctly. That way I can pop a drive into the dock and let it hum away in the background checking the files without having to manually load discs one after another. If anything goes wrong with one drive I'll know - then I can replace the bad drive and recover the files from the other drive. This avoids the fatal flaw in optical disc backups - people never bother to check all of them them to ensure that they're still readable because of the manual work involved.


Hi sminlal,
Can you please explain how and what util you are using to checksum your data? would be very interested..!
Many thanks in advance..!
m
0
l
!