Ok, the real question, please dont shoot me.

[johnbot]

Ok so here is my setup:

 

1 backup server

10 client systems

 

I used the easyscipt setup and followed its recommendations. I now have 2 backup sets (backup set A and backup set which are set two alternate every day. (M-F) . Here are the questions which I'm hoping someone can help me with.

 

1. since i have two backup sets, will the first backup run in both sets A and B contain FULL backups? I assume they will.

2. Assuming that the tapes in both backups will contain FULL backups when first run, I assume the next backups will write incremental (normal) , appending the data to these same two tapes?

3. what if i want to take these tapes out of the loop everyweek and store them offsite, how do i tell the backup software that I want to use new tapes for both backup sets every week?

4. will using new tapes each week cause more and more members to be added to backup set A and B? (which i would not want, just want to replace them)

5. finally, does anyone have any other suggestions for doing this (i.e. i want to backup the backup server and clients every night and then take a copy offsite for safe storage)

 

Thanks for any assistance you can give me.

 

John (confused)

 

[mcswgn]

Quote:

---

1. since i have two backup sets, will the first backup run in both sets A and B contain FULL backups? I assume they will.

 

---

 

Yes. Backup sets are independent. A Backup set will always try to write all files not previously written to it, so the first time round that will be everything--and it doesn't matter how many other backup sets have the same data.

 

Quote:

---

2. Assuming that the tapes in both backups will contain FULL backups when first run, I assume the next backups will write incremental (normal) , appending the data to these same two tapes?

 

---

 

Yes and no. It's incremental in that files that haven't changed since the previous backup won't be written again. But it is not an incremental in the traditional sense. Retrospect notes the exact status of the disk (the "snapshot") and then for each file either writes it to the tape (if not done so previously) or marks its location on the tape if it's already there. In this way a full restore can be made from just the one snapshot--unlike a traditional incremental that cannot be used for a full restore.

 

Quote:

---

3. what if i want to take these tapes out of the loop everyweek and store them offsite, how do i tell the backup software that I want to use new tapes for both backup sets every week?

 

---

 

You would need to introduce additional backup sets: A2, A3, ..., B2, B3, ... All the A's would run on the same days of the week; all the B's on the other days of the week. When the tape(s) for a specific backup set come back from off-site to be reused, set the media action to "Recycle". If the tapes are to stay off-site and not come back eventually for reuse, then it would be easier to use "New Media". This will make a slight change to the name of the backup set (Backup Set A -> Backup Set A [001]) and allow you to start from scratch with the new backup set without having to go and manually define the additional backup sets.

 

Quote:

---

4. will using new tapes each week cause more and more members to be added to backup set A and B? (which i would not want, just want to replace them)

 

---

 

A set of tapes represent a specific backup set. As long as that same backup set is being used, the number of tapes will continue to grow. But if you are intending to rotate tapes off-site, then you would be using multiple backup sets, not one. If you bring a set back and do NOT set it to Recycle, then it will continue on from where it left off the last time it was used (and continue to add tapes). Recycle tells Retrospect to dump all of the old data from the backup set and start it over, reusing the old tapes in the process.

 

Quote:

---

5. finally, does anyone have any other suggestions for doing this (i.e. i want to backup the backup server and clients every night and then take a copy offsite for safe storage)

 

---

 

If you have an autoloader, then it makes sense to define certain sets to run on different days, since both sets can be left available all the time. But if you don't have an autoloader so that you are having to swap tapes manually, then it makes more sense to not use these restrictions. Retrospect will write to whichever backup set has its tape in the drive, so you can allow all backup sets to run everyday, but swap tapes to whichever one you want that night. This will reduce the number of distinct backup sets you need to create.

[Rascii]

Quote:

 

Yes and no. It's incremental in that files that haven't changed since the previous backup won't be written again. But it is not an incremental in the traditional sense. Retrospect notes the exact status of the disk (the "snapshot") and then for each file either writes it to the tape (if not done so previously) or marks its location on the tape if it's already there. In this way a full restore can be made from just the one snapshot--unlike a traditional incremental that cannot be used for a full restore.

 

Question:

 

I guess I'm still in the dark. If I have one default "backup set" and use 5 tapes (Mon-Fri), would only the first tape used be a full copy and the rest contain any changes? Or will a normal backup put the whole backup on the tape if it is blank. (so you would have 5 tapes with a full backup image and then when you came back to that tape the second and third week, etc. you would only then add the changed files, but each tape would initially get the full backup?)

Thanks for any clarification.

[mcswgn]

Perhaps it would help to compare/contrast to a traditional "dump" backup.

 

In a traditional backup you have a "dump level". When you run a backup at level X the system will write to tape all files created or modified since the last backup of level X-1. (So level 1 goes back to the last level 0, level 2 back to the last level 1, etc.) You would start a backup with a level 0 (gets everything), then the next day you would run a level 1 to a second tape. This is the "incremental" and gets everything that has changed in the last 24 hours. To completely restore a system you would work in the same order: first restore the level 0 (this puts back everything, but some files are 24 hrs out of date), then restore the level 1 on top of the level 0 (this fixes the out of date files). If you want to restore a single file you need to first guess if the file changed within the last 24 hrs. If not, you need to go to the level 0 tape to get it. If so, you want to use the level 1 tape. If you go to the level 1 tape first and you were wrong, the file isn't there at all. If you go to the level 0 tape first and you were wrong, the file is there but it's the old version (which you don't realize because you didn't think it had been modified in the last 24 hrs). Because it is so important to know when the dump was made, one typically would use a different tape for each dump/night even if all of the data from different dumps would fit on a single tape. It's bad enough having to skip forward in a tape to get the correct dump file from a single night dumping various partitions, but it would be a mess if you had to keep track of which night they came from as well.

 

Retrospect is completely different. First, you really would not want a different tape for each night. You have one "backup set" that may span several tapes, with tapes being added as each fills. The first night it might take multiple tapes to do a complete backup, and then it may never need to add another for the rest of the week. It's possible to force it to start a new tape every night, but that's working against the grain and would require extra work on your part. Retrospect wants to just keep working on the tape it has until it's full. Unlike a traditional system where each tape is really independent, a Retrospect backup set is one single entity that is not to be broken up. It needs the entire set for any sort of restore (although it doesn't necessarily pull things off every tape every time). When retrospect does a backup the first thing it does is scan the entire disk. This gives it a complete accounting of all files on the disk as of that instant. This is stored as a "snapshot" that allows you to restore to the same state at a later time. It then does two things. It applies any selectors you have in case you are not asking it to backup the entire disk (but note it *knows and saves* the status of the entire disk whether you are backing it all up or not) and it looks at its catalog to see how many of these files it already has in the backup set. So if right now your disk has a file "important_doc" that was created/modified on certain dates and of a specific size, etc it will scan the catalog looking for that file. (This is what it's doing when it says it is "matching".) It may exist in the backup set already because it was on your disk the last time it was backup up, or maybe it was on your boss' disk on a previous backup. It doesn't matter where it came from. It knows it needs this file to rebuild your disk to its *current* state; it either has it on tape already or it doesn't. If it does, it notes where on the tape it's located. If it doesn't it appends it to the backup set (writes it to the end of the currect tape) and adds it to the catalog.

 

Now you can also set up independent backup sets, each using its own stack of tapes. You could for example create named backup sets "Monday", "Tuesday", etc. And use a different backup *set* each night (although I wouldn't recommend it--too much swapping of tapes, but having this for a weekly rotation makes sense). A backup set needs to be created. Once created, retrospect will manage the tapes that are contained in it. When you put a tape in that belongs to a backup set, retrospect knows which set it belongs to and will use that backup set & catalog for doing backups to the tape. Different sets are independent though. If "important_doc" is in your "Week 1" set and then you switch to backing up to set "Week 2", it won't matter that "important_doc" is already in Week 1. Week 2 must be self contained and so if it's not yet in Week 2 it will be put there.

[Rascii]

Thank-you for your very insightful and detailed reply's. I'm starting to understand. I guess my backup plan for Retrospect is messed up. I have 5 tapes (mon-fri) running as backup set A, with fridays being a recycle. What your saying is it would be best if I used one tape only until it was full and then add other tapes as needed. I assume then if the tape is full there would be a message on the screen in the morning telling the user to insert a clean tape and the backup would then finish. Are there any other resources that I could investigate for Retrospect stratigies other that what is posted on there site?

 

Thanks again for your help.

[mcswgn]

Quote:

---

What your saying is it would be best if I used one tape only until it was full and then add other tapes as needed.

 

---

Yes, although there are times when you may want to skip the rest of the free space on the current tape and go onto the next. For example, the first time a backup set is used it will use a lot more media than later times. After you get some experience with the amount of data you have to be backed up and how much you can get on a tape, you may find that tapes are always running out at about the same day everytime. So in that case when the tape is almost full you might want to skip onto a new one so it will have a fresh tape to start the night and you don't have to worry about it running out in the middle. To skip to a new tape select the "Skip" option under Media Action. This will mark the rest of the current tape as unavailable and then be ready to accept a new tape to continue.

 

Quote:

---

I assume then if the tape is full there would be a message on the screen in the morning telling the user to insert a clean tape and the backup would then finish.

 

---

That is correct. Whether it will continue or not, though, depends on whether the hours during which the script runs have expired (i.e. if the backup runs 10pm to 6am and you come in at 8am it will have already aborted) and whether you have set a "Media Request Timeout" in the preferences. If you set a timeout and it doesn't get a new tape within that period of time then it also will abort. If it is absolutely critical that the backup complete every night, then you would probably want to be more conservative on setting things up. There is nothing wrong with starting with a new tape each night except that it increases the media use. I would say at first you should just let it run without skipping to new media each night and get a feel for how much is backed up each night and how much on average you can fit on a tape. (For example, we use DDS3 tapes which are advertised as 12GB uncompressed and 24GB compressed. We pretty consistently get 13-17GB compressed on each tape.) Once you know that you can fine tune things to fit your setup. However, if you can get your first full backup all on one tape, it is almost certain you will be able to fit the entire rest of the week on a second tape unless you are in some sort of multimedia company where huge new files are created every day.