How much disk space is each client using

[jmurgol]

Is there a way to see how much each client is using in Retrospect enterprise. I can see the backup reports but it seems to be giving me individual backup information. I need to see how much a machine is taking up disk space wise in totality.

 

Thanks

 

James Murgolo

[Lennart_T]

I don't think you can do that.

Let's say you have an identical large 10GB file on three clients. The file is backed up once per Backup Set

So, how much space does each client use? Well, the first backed up client uses 10GB and the others nothing. Assuming you have a Disk Backup Set on a large disk and can groom the backup set. The 10GB file isn't groomed until ALL snapshots containing the 10GB file is removed (one way or another).

[mauricev]

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Let's say you have an identical large 10GB file on three clients. The file is backed up once per Backup Set

 

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Wow. What version of Retrospect are you using? 9?

 

What you are describing is a technology called de-duplication, which is popular in enterprise backup programs because it saves a huge ton of disk and tape space, and it would be fantastic if Retrospect had it, but it doesn't.

 

So in the case above, the file is backed up three times.

[Lennart_T]

Just try it for yourself. Create a new backup set. Backup two clients, as similar as possible (same hardware, same OS, same files, same applications). Look in the log: How much data was backed up for the first client? How much data was backed up for the second client? Compare the latter number with the amount of data on the second client's hard drive. You will see a large difference.

 

EDIT: Please see:

http://kb.dantz.com/al/12/1/6173.html

[rhwalker]

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it would be fantastic if Retrospect had it, but it doesn't.

 

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I've been using that feature since Retrospect 2.0 in 1992.

[mauricev]

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I've been using that feature since Retrospect 2.0 in 1992.

 

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Perhaps I should downgrade

 

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Just try it for yourself. Create a new backup set. Backup two clients, as similar as possible (same hardware, same OS, same files, same applications). Look in the log: How much data was backed up for the first client? How much data was backed up for the second client? Compare the latter number with the amount of data on the second client's hard drive. You will see a large difference.

 

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Huh? The snapshots among clients are independent. So it will backup both systems twice and there won't be any difference.

 

I am puzzled as to how you are managing to obtain such a feat when this feature is relatively new even to enterprise-level backup programs.

[rhwalker]

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The snapshots among clients are independent.

 

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Well, no, not if the same files are on multiple clients. See, for example, page 242 of the Retrospect 7.5 User's Guide ("Don't add duplicates to backup set").

[Lennart_T]

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Huh? The snapshots among clients are independent. So it will backup both systems twice and there won't be any difference.

 

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Why do you just assume you are right without even trying? There WILL be a difference. And you didn't even read the knowledge base article. (sigh.)

 

The snapshots just references the files in the backup set, a list of the clients files if you wish. An identical file will be listed twice (once for each client), but only backed up once.

 

It seems as the "enterprise-level backup programs" are years behind...

[mauricev]

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Well, no, not if the same files are on multiple clients. See, for example, page 242 of the Retrospect 7.5 User's Guide ("Don't add duplicates to backup set").

 

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This option just seems intended to make backups incremental (on a per client basis and it seems to be on by default).

 

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Why do you just assume you are right without even trying? There WILL be a difference.

 

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Why do you assume I didn't try? For the record, there is no difference. Every file gets copied twice. Really!

 

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The snapshots just references the files in the backup set, a list of the clients files if you wish. An identical file will be listed twice (once for each client), but only backed up once.

 

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This is true for snapshots among a client, but not across clients.

[Lennart_T]

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Why do you assume I didn't try?

For the record, there is no difference. Every file gets copied twice. Really!

 

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Now THAT'S puzzling. It seems as there is something wrong with YOUR setup. We use Disk Backup Sets and backup to NAS servers that simply doesn't have the disk capacity to store all data for all clients. The redundant files are NOT backed up.

 

Are you using "Duplicate" and not "Backup" in Retrospect? Those are different. Only when using "Backup" will a file be backed up only once.

 

There is an option in Retrospect where you can force it to compare the location of the file as well as the date/time/name/etc. Is that option turned on? Then turn it off.

[mauricev]

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Now THAT'S puzzling. It seems as there is something wrong with YOUR setup. We use Disk Backup Sets and backup to NAS servers that simply doesn't have the disk capacity to store all data for all clients. The redundant files are NOT backed up.

 

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As far as I can recall, our Retrospect versions has never worked the way you are describing. And I probably started with the original version on the Mac, though I honestly don't remember it from all those years back.

 

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On Windows, Retrospect looks at creation date and time, modified date and time, size and name.

 

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If Retrospect really used such an algorithm, it's bound to fail at some point. Times are not necessarily synced among computers, and if a file is changed with a single character such that the size does not change and if it just happened to have the same modification time as a different, but otherwise identical file on another client, Retrospect would erroneously skip it. There is too much risk of coincidentally files appearing to match. Indeed, enterprise backup level programs are probably maintaining tables of hashes for the files to ensure files don't get duplicated, but also not missed.

[Lennart_T]

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On Windows, Retrospect looks at creation date and time, modified date and time, size and name.

 

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If Retrospect really used such an algorithm, it's bound to fail at some point. Times are not necessarily synced among computers, and if a file is changed with a single character such that the size does not change and if it just happened to have the same modification time as a different, but otherwise identical file on another client, Retrospect would erroneously skip it. There is too much risk of coincidentally files appearing to match.

 

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I don't get it. Let's say a file have creation date D and modification date E. The file is copied to another client. A backup runs and the file is backed up once (but it appears in two snapshots). Then a single byte is changed on one of the clients and saved (with modification date F). Then you have one file on one client with dates D and E and another with dates D and F. The latter will be backed up since it's changed. What do you mean it won't be backed up? Even is F is off "actual" time by several minutes, it's bound to be backed up.

[mauricev]

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Then a single byte is changed on one of the clients and saved (with modification date F). Then you have one file on one client with dates D and E and another with dates D and F. The latter will be backed up since it's changed. What do you mean it won't be backed up? Even is F is off "actual" time by several minutes, it's bound to be backed up.

 

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What if the clock on that client is slightly off such that the time it gets modified just happens to be time E? That is, F = E. So now we have two files with name, size, date created and date modified but different data? It's not easy for this to happen, but it could happen theoretically and the more clients in a backup set, the more likely it is.

 

(Of course, on my Retrospect, this file would get backed twice because each client is gets treated independently. )

[Lennart_T]

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It's not easy for this to happen, but it could happen theoretically and the more clients in a backup set, the more likely it is.

 

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"not easy" is an understatement. I would say it's practically impossible.

[mauricev]

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"not easy" is an understatement. I would say it's practically impossible.

 

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On a single client, that is probably true.

 

Also, there may be other circumstances that we don't know about wherein files on different clients may match in every respect but their content, especially with OS files.

[Lennart_T]

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there may be other circumstances that we don't know about wherein files on different clients may match in every respect but their content, especially with OS files.

 

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Surely you are putting me on? Have you ever heard of an OS file with the same name, the same size and the same dates that doesn't have the same contents???

[mauricev]

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Surely you are putting me on? Have you ever heard of an OS file with the same name, the same size and the same dates that doesn't have the same contents???

 

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No, but I haven't not heard of it, either. It wouldn't shock me if this situation existed somewhere.

 

The backup companies that advertise this functionality in their programs go by the bytes of the file, although their functionality exceeds what your copy of Retrospect does.