ReCycling Tapes

[obryant32]

This may be a dumb question, but I'm new to Legato, the most confusing backup software ever. Anyway, I'm currently running my backup where I have a 5 tapes in my autochanger and each tape is set to run incrementally on a specific night. For example tape1 runs Monday, tape 2 runs Tuesday, etc. However all my tapes are full now and I'm not sure what to do. Should I just relabel them? I'd tend to think no, because then I'll lose my backups for the last month. Is there a way to somehow recycle the tapes without losing all my backups? Or, should I simply get all new tapes and store the other ones somewhere else? If that's the case though, will that screw up my other tapes.

I'm just completely confused. Can somebody perhaps reccomend a good Legato Book or direct me to a link that will help me best backup practices. Please help, my boss won't spring for support and I'm completely lost with this product. Thanks

Matt

 

[goony]

Legato has a concept of backing up to a 'pool' of tapes - unless you are removing each day's tape to take offsite, it is OK to allow Legato to write again the next day on the same tape. If your daily backups are modest, it is possible that you could get 3, 4, 5 or more days onto a single tape.
Legato keeps track of it all and knows what backups are on what tape cartridge.

Tapes in a pool can be in the autochanger, or stored nearby- but they are still part of the pool.

When you do a data restore Legato will know what tape(s) to ask for... they need to be in the autochanager or close by so you can put them in there.

How many tapes you will need in your 'pool' will largely be determined by your browse and retention settings (read up in the docs for this) and, of course, how many systems, how often you do full backups, etc.

A tape volume will become eligible to be 'recycled' (overwritten) once every saveset on that tape has expired. These savesets expire based on your browse and retention settings. If you plan on (say) retaining data for a year, then you will need lots of tapes. If your retention is set much lower (a week or two) then you will need far fewer tapes.

Yes, Legato can be a bit daunting at first but once you understand its concepts (it took me a while of just playing with it and reading all of the docs) you will do just fine.

I suggest that you step back and not try to force Legato to 'do backups for you the way you always did', instead look at it as "For each system (client) that I need to back up, 1) how often do I need to do a backup 2) how often do I need to do full backups(*) 3) how long do I need to keep the data 'very handy' for a recovery and 4) how long do I need to keep the data before I can overwrite it."

(*) Full backup frequency just depends on how important it is to you to quickly recover your data. One extreme would be a full backup every day (or, with Legato, you could do it more often than that!), the other extreme would be (say) one full backup a month, and some kind of incremental scheme in between. The downside of infrequent full backups is the recovery time required if you would lose a disk that hadn't had a full backup performed for 30 days- a lot of tape jockeying just to get the data back to its most recent state.

Where I work we happen to do once-a-week full backups and incrementals on the other days. If you go longer than a week between full backups then I strongly suggest you study the numeric 'backup levels' and how to implement them. That may mean far fewer tape recoveries than my extreme example above of 1 Full + 30 incremetal restores.

 

[goony]

As I pointed out before, you need to know how long data from each system must be kept. People use backups for different reasons: 1) My disk drive failed, I need to recover from my most recent backups so that I have a good, usable disk again or 2) Mr. Peabody wants us to restore the January, 2003 data files into the XYZ directory on system ABC for a special audit starting in 30 minutes.

If you figure out that you have client systems that have disparate retetion periods (i.e. most systems= 2 weeks, a couple of systems= 1 year), then I would hihgly suggest creating separate tape pools. Thus, if all systems with short retentions go into one pool, then the volumes would become recycleable much quicker and could be reused. If you don't do this, then you could have a single tape with 97% of the savesets expired (i.e. could be overwritten) and 3% of the savesets waiting for a full year to exprire - result: Legato will not reuse that tape until ALL savesets have expired - a genuine waste of tapes.

 

[605]

Well, in fact NW is easy to handle once you understood the
concept. However, i guess you have been biased by other
backup systems an i agree, this makes it hard to switch to a
different concept.

NetWorker will only recycle tapes automatically, if all the
save sets on the tape passed their retention period AND NW
needs it. If you relabel the tape, you will loose all info.

In fact, your concept using an incremental tape for every
day does not really make sense (from NW's aspect).

With respect to cutting the learning curve, may i suggest
that you either attend a training course or you download
the file TIDS_2002.PDF from Legato's PartnerNet web site
(your Legato partner should e able to provide it).

 

[obryant32]

Believe me, I would love to be able to go to a class but I work for a very cheap boss. Could you please recommend any good classes or books that could help me out. I'd appreciate it greatly.

Matt

 

[goony]

I forgot about that one... the TIDS_2002.PDF file is a great start... see if you can get it from somewhere.

 

[speculos]

You can find the TIDS_2002.PDF (and others) there:

ftp://ftp.legato.com/pub/NetWorker/German/tdocs/

(you don't need to speak German to understand...)