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Snapshots faster in 7.5?


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I'm currently running 6.5.350 and am evaluating 7.5.10.104 on our new backup server. I was quite excited to hear that snapshots creation times had been reduced, so I tried a quick test to see..

 

On my new server with Retrospect 7.5 I created a new backup set, upgraded the agent on my FS to 7.5.116 and then performed a backup of one of my somewhat larger volumes. This backup script included the backup of "security information from servers".

 

-3/10/2007 9:38:29 AM: Copying Volume on FILESERVER

3/10/2007 7:04:08 PM: Snapshot stored, 122.3 MB

3/10/2007 7:04:16 PM: Execution completed successfully

Completed: 226877 files, 117.9 GB

Performance: 227.4 MB/minute

Duration: 09:25:47 (00:35:12 idle/loading/preparing)

 

Then when I go to backup that volume again, with the same backup "Options", including NTFS security information, it copies the few files that have changed. However, when it proceeds to "building snapshot", I expected the filenames of only the files that have changed to scroll across the screen, but it starts going through the entire volume again. shocked.gif Hmmmm, I said. So I just let it finish...

 

- 3/12/2007 10:51:42 AM: Copying Volume on FILESERVER

3/12/2007 11:33:27 AM: Snapshot stored, 123.7 MB

3/12/2007 11:33:52 AM: Execution completed successfully

Completed: 12 files, 2,348 KB

Performance: 3.2 MB/minute

Duration: 00:42:10 (00:41:27 idle/loading/preparing)

 

Is this expected behavior? I was expecting something like 5 minutes? I know 42 minutes isn't the end of the world, but it adds up!

 

Here is the log file from the same volume under 6.5:

 

- 2/28/2007 12:57:51 AM: Copying Volume on FILESERVER

2/28/2007 2:19:39 AM: Snapshot stored, 121.4 MB

2/28/2007 2:20:16 AM: Execution completed successfully

Completed: 24 files, 4,042 KB

Performance: 4.8 MB/minute

Duration: 01:22:20 (00:28:42 idle/loading/preparing)

 

Yes... It's faster on the new system, however the new system is 4x faster. smile.gif

 

 

Am I missing something??

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I have only compared 7.5 vs 7.0 and 7.5 IS faster.

 

By the way, the 42 minutes you write about includes scanning time, which is the same for 7.0 and 7.5.

 

And even if a file's CONTENTS haven't changed, you might have changed file/folder permissions, so the snapshot must check all files/folders, not just the ones whose contents has changed.

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Yes, I understand that the only way for it to determine what has changed is for it to perform a complete scan at the beginning of the backup job, and yes that process probably took about 15-20 minutes, the backup about 1 minute for the 2,348KB and then 21 minutes for the rest (snapshot?). I was expecting the 21 minutes or so at the end where the snapshot is created to take <5 minutes as it's only having to add 12 files to the snapshot?

 

This assumption is based off a quote I saw from 'natew', who is somewhat of an authority, yes??

 

From thread: http://forums.dantz.com/ubbthreads/showf...0&fpart=all

 

"In 6.5 and 7.0, Retrospect has to open every single file on disk to collect security information to build the snapshot. This happens regardless of if you are doing a full or incremental backup.

 

Retrospect 7.5 only needs to open new and changed files when creating the snapshot. Obviously that will drop the snapshot creation time dramatically."

 

 

So I assumed that when it goes to build the snapshot only the "new and changed files" would be needed (12 files), but as previously mentioned I see more than 12 file names "fly by" when it performs the snapshot.

 

 

I'm just trying to fully understand what is going on and if this is the expected behavior...

 

Thanks all,

 

-g

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Oh... Well I don't know how to interpret that quote from natew then, it seems to contradict what you've said and what we're seeing... Maybe now it scans every file, but only has to "open" the files that have changed when building the snapshot? Ugh!

 

I guess the general consensus is it's faster, I'm just not fully certain why...

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Quote:

"In 6.5 and 7.0, Retrospect has to open every single file on disk to collect security information to build the snapshot. This happens regardless of if you are doing a full or incremental backup.

 

Retrospect 7.5 only needs to open new and changed files when creating the snapshot. Obviously that will drop the snapshot creation time dramatically."

 


 

I'm not exactly clear why it would have open these or any files. What do they have to do with their security information? OTOH, how does it manage to avoid skipping all those other files? It seems it would have to check every file's metadata twice, once to determine whether the file has been just created or changed and also to gather its security information. That scenario may vary depending on which OS and which version of that OS the client is.

 

In any case, I had been seeing snapshot building in 7.5 taking a very long time on old disk sets. But at the moment with new fresh disk sets, it's not..yet.

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