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[#] Wed May 02 2007 13:12:49 EDT from IGnatius T Foobar @ Uncensored

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I rotate my tapes every two weeks so it doesn't matter.

As far as burning new CD's ... yes, that would work fine. However, a large portion of the people who are using removable media for *archival* purposes do not intend to continue keeping that data available in their online storage.
This is a problem.

So ... make two CD's or DVD's of everything, and re-burn them every year or two? I suppose that would work but it wouldn't be practical on anything but the smallest scale.

[#] Wed May 02 2007 23:20:41 EDT from Animal @ Uncensored

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why not just use a hard drive?

[#] Thu May 03 2007 00:44:34 EDT from nadia @ Uncensored

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here's the thing though, it's common to rotate tapes as such, but is the paradigm totally different for rewritable discs?

re hard drives: i don't know. stripe and mirror to maintain data integrity (or whatever you call it) but archiving is a different paradigm? i don't know at all.

[#] Thu May 03 2007 09:35:17 EDT from Ian M. Shot @ Haven BBS

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If in a small enterprise I have 1.5TB of data to back up, how many DVDs is that?  How about Drives?  Max size on IDE drives right now is 750GB, which is around half, so I only need 2 drives.   However that also means a total of 3 - 4 drives per week, and a total of 15 - 20 drives per 5 weeks, and an additional 18 to 24 drives for 6 months of end of month backups.  So a total of potentially 44 drives for backups.  So at $250 per drive * 44 = $11,000 for backup media.   Plus hard drives are heavy compared to tape.  LTO-4 is 800GB native, and much smaller in wieght than hard drive.   Also the tape is only $150 per  tape.  So 44 *  $150 = $6,600, so a savings of $4,400 in media costs. 


3 - 4 drives per week is 1 or 2 Monday - Friday for Incremental, 2 drives for a full backup on the weekends.   Also don't drop the Hard Drives, they might scratch the platters.  Also depending on where you store your off-site backups you may need more space since Hard Drives are larger than tapes. 

[#] Thu May 03 2007 09:38:10 EDT from Ian M. Shot @ Haven BBS

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One point I forgot is that Tape is one of the only viable means of line of business data recovery available.  Hard Drive would be the other one, but as I stated, storage and transport are the issues, just because hard drives are larger and heavier than tapes. 

 Tapes can be taken off site so if the building is destroyed the data can be recovered from tape and be only a week old.  This could be done with Hard drive too, but again expense, storage are issues. 

[#] Thu May 03 2007 09:44:23 EDT from fleeb @ Uncensored

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If you have 1.5 TB to back up, you don't want to use DVDs.

They only hold about 2 gigs.

You would spend an awful lot of time burning DVDs, and not actually doing anything productive. 

[#] Thu May 03 2007 09:47:33 EDT from fleeb @ Uncensored

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You have some other options available to you, perhaps:

  1. Back up less data.
  2. Use an off-site storage solution that backs up data via internet rather than tape or drive.
You probably think you can't do #1... and maybe you can't... but it's really your best option.  Often, when you start to seriously think about what you're backing up, you'll find you're backing up an awful lot of nonsense that doesn't need backing up (e.g. ghosted images of hard-drives are silly to back up, when you really only need to back up dynamic data, like documents and source code).

[#] Thu May 03 2007 09:55:54 EDT from triLcat @ Uncensored

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I noticed that companies I worked for often backed up *WAY* more than we needed to.

However, when I worked for a publisher, there were daily changes to literally 20-30 books, including images and the audio & software that went with them.
 (The company published educational books which often comes with software and almost always comes with audio)

[#] Thu May 03 2007 10:06:15 EDT from fleeb @ Uncensored

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Ideally, when thinking about backup, you should identify two types of data.

One type is dynamic... data that changes a lot over time.  You create new documents, source code, pictures, databases, e-mail, or whatever it is your company generates by way of data that people eventually examine in some fashion.

Another type is static... the operating system, programs you use to work with dynamic data, and perhaps firmware for your devices.  This data doesn't tend to change very much.

Once you identify these two types of data, you should be able to backup the static data on rare occasions when it changes (you've updated to a new version of Spiffy-Doc, The Doc Mangler), and often you don't even need to back that out to some other office.  The dynamic data is usually much, much smaller than repeatedly backing up the static data, and becomes more manageable as a consequence.

Once you've made this kind of separation, you have a question as to how you go about restoring a machine.  You'll want some kind of process in place where you can rebuild a machine's software from scratch (lay down the OS, and install all the applications), as well as restore the dynamic data (documents, shortcuts, etc).

My last company provides part of the solution, in handling the 'static' data for you, as well as some of the dynamic data (shortcuts, and other such profile information), but doesn't really handle the traditional backups portion.  But, unfortunately, they're a Windows-only solution... you can probably cobble up something for Unix fairly easily, though. 

[#] Thu May 03 2007 10:40:02 EDT from Ragnar Danneskjold @ Uncensored

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I do a combination of tape and disk.....

Disk backup is the front line. It's fast to back up to, and fast to restore from. There's always a couple of days worth of data on disk.

Then we migrate out to tape.

In order to keep tape heads going fast, we run multiple heads simultaneously, and stripe across them, just like a RAID set....

Retention time is another issue.... Are regulatory issues at hand? You may be saving data for 7 years then..... And that's where tape really starts to make sense.

Compression algorithims help quite a bit too. We're getting about 1.6:1 compression.

[#] Thu May 03 2007 15:55:21 EDT from Ian M. Shot @ Haven BBS

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Those were the points I was trying to make.  The discussion on backing up to CD/DVD works only on a personal level, and not on an enterprise level.  Hard Drive really only works on a personal level also.  When I posited 1.5TB of data to backup, I didn't say anything about the OS.  I don't care about backing up the OS.  I can recreate and reload that, same with MOST applications.  Some applications I will back up because of the complexity of the application. 


To give an idea, I have to back up our Database server in full every night because it has our accounting data on it, and we decided that this was important enough to do a full backup on the databases.   So I snag the DBs off and have full copies.  The accounting program I have to back up only the reports when they change, so I only grab incrementals except on the weekends when I grab the whole thing.


So what I was trying to show was that tape makes sense in the Enterprise and DVD and Hard Drive do not make sense, at least not in the Enterprise.    But this is where I spend the majority of my time. 

[#] Thu May 03 2007 16:19:31 EDT from wizard of aahz @ Uncensored

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Ian - Just out of curiosity, if it's databases needing backup why not use replication?

[#] Thu May 03 2007 16:55:08 EDT from Freakdog @ Dog Pound BBS II

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If you have 1.5 TB to back up, you don't want to use DVDs.

They only hold about 2 gigs.

Basic single density DVD is 4.7GB

[#] Thu May 03 2007 17:44:26 EDT from Magus @ Uncensored

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Freak, so one only needs half of way too many DVDs to use them for backing up 1.5 TB?

[#] Thu May 03 2007 18:47:38 EDT from steve @ Uncensored

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Ian - Just out of curiosity, if it's databases needing backup why not

use replication?

Replication isn't a backup. It allows business continuity if, for example, your primary database server has a hardware failure.
However, if you delete 6 months of critical financial transactions from your database, well that too will get replicated to your other server. /then you have to get out your backup tapes to restore the lost data.

[#] Thu May 03 2007 18:54:16 EDT from Freakdog @ Dog Pound BBS II

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Freak, so one only needs half of way too many DVDs to use them for
backing up 1.5 TB?

Exactly!!! ;-)

[#] Thu May 03 2007 21:06:04 EDT from IGnatius T Foobar @ Uncensored

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steve's got the right idea. "Backup" and "Disaster Recovery" are tangentially related but they are NOT the same thing.

[#] Thu May 03 2007 21:14:10 EDT from Ragnar Danneskjold @ Uncensored

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You could replicate your dump to another machine offsite.... :)

[#] Thu May 03 2007 22:55:17 EDT from Magus @ Uncensored

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And neither is the same as "data archive". We produce somewhere on the order of 500 GB of data per day. We can't keep it all live on our servers, so we have to have some kind of archive scheme where we can put it somewhere that we can get at when we need it. This is sort of like backup, except with perhaps a greater implication of permanence. (Also, the "backup" is the only copy)

[#] Fri May 04 2007 00:31:53 EDT from wizard of aahz @ Uncensored

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steve is correct - the difference between replication and backup. We tend to back up our replicated data every evening.. Just for convenience. One thing Magus hasn't mentioned about archiving data is the need to UNARCHIVE the data from time to time when you decide you want something back. Sometimes it's not worth it.. To quote IBM... Disk is cheap. <GRIN>

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