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Slow network backup time


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I'm using the 8.0.733 version running on Mac OS X 10.5.5, backing up to a VXA-320 StorageLoader. This version doesn't crash repeatedly like the previous 8.0 release, so that's progress.

 

I was able to successfully complete my first local disk backup to tape. Here is a performance comparison, according to the log files of 6 and 8, backing up the same data:

 

Retrospect 6.1.230:

 

Completed: 886624 files, 40.4 GB

Performance: 289.1 MB/minute (246.6 copy, 349.2 compare)

Duration: 05:33:57 (00:48:20 idle/loading/preparing)

 

Retrospect 8.0.733:

 

Completed: 864806 files, 30.8 GB

Performance: 519.3 MB/minute (541.6 copy, 499.1 compare)

Duration: 02:55:45 (00:55:24 idle/loading/preparing)

 

Now, I'm a bit concerned that it backed up 20,000 fewer files and 10 GB less, given that I tried to copy my selector over as a rule correctly - I'll have to track that one down, it could be my error. The performance has shot up from 289 MB/min to 519 MB/min - almost double! That's great!

 

 

Then I tried my first proactive backup, backing up a MacPro running 10.5.7 with client 6.3.019. The MacPro is on a switched gigabit wired LAN, same subnet as the Retrospect server, which is also gigabit. The client was added by IP address. Here's the same comparison:

 

Retrospect 6.1.230:

 

Completed: 1819886 files, 115.8 GB

Performance: 361.4 MB/minute (289.4 copy, 481.2 compare)

Duration: 12:34:00 (01:37:58 idle/loading/preparing)

 

Retrospect 8.0.733:

 

Well, unfortunately, I can't tell you how fast it went from the log file, because it didn't get logged after I stopped it manually:

 

5/17/2009 10:15:50 AM: Execution stopped by operator

Remaining: 32294 files, 7.4 GB

Completed: 0 files, zero KB

Performance: 0.0 MB/minute

Duration: 00:02:49 (00:02:48 idle/loading/preparing)

 

All of that information is incorrect. I can tell you that I had the backup running for over 8 hours, and it had only backed up around 65GB, and the status bar indicated it was backing up at around 150MB/min, and by my estimate it had at least 6 more hours to go before it completed writing the data before it would start verifying. The tape drive was idle more often than it was writing (which also wastes tape capacity.) The client machine was a Mac Pro 3GHz quad core, and was idle during the backup, so it wasn't being bound by the client or its network segment.

 

My network switch showed that the data was coming into the server averaging around 22 Mbps, which isn't breaking a sweat for a gigabit switched network.

 

This network backup performance was more than twice as slow as 6.1. It's so slow that I would not be able to complete my set of daily proactive backups within a 24 hour period, which means that I have to once again switch back to 6.1.

 

Is this a known issue? Is it being addressed?

 

Thanks,

-Mike

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Here's a proactive backup from a windows notebook to retrospect 8. Speed seems about the same as retrospect 6. And like version 6, the speed seems to depend on the client.

 

Completed: 17600 files, 3.0 GB, with 4% compression

Performance: 219.5 MB/minute

Duration: 00:16:47 (00:02:53 idle/loading/preparing)

 

Here's another one from another windows notebook:

 

Completed: 151 files, 1.7 GB, with 7% compression

Performance: 371.3 MB/minute

Duration: 00:08:30 (00:03:58 idle/loading/preparing)

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I'm seeing much slower speeds to a networked client. (My MBP over gigabit ethernet on Cat5e-FTP, to an Airport Express, to 802.11n-only 5Gz, to an iMac client.) Like 30MB/minute. Incredibly slow on small files.

 

There have been so many posts about backup speeds that I can't keep up with them all.

 

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I posted some stats from what I was able to test here. Basic results were:

 

1) Retro 8 is really slow on tiny files -- but so is Retrospect 6

 

2) Turning off the MD5 checking in Preferences speeds up Retro 8 backups noticably.

 

3) In general (for me at least -- backing up to a "disk media set" on an external FW drive), my backups were only *slightly* slower than Retrospect 6 backing up to a "file" set.

 

It sure appears to feel slower, but I don't know how much it really is...

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Oh, and I posted all my test results here;

 

http://forums.dantz.com/showtopic.php?tid/30638/

 

 

I'd be *really* interested in seeing other people do a comparison along the same lines as to what I did...

 

 

And, yes, it would be nicer if Retro 8 could back up smaller files faster as that's what a lot of my backups are (tiny iCal event files...)

 

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Maser, thanks for the summary!

 

I want to say something here about how R8 shouldn't have been released while its performance wasn't completely understood. But I guess that would just be piling on, so I'll shut up. I fervently hope that definitive performance advice / metrics are forthcoming soon, and also that they can address any bottlenecks soon.

 

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  • 2 weeks later...

Since the VXA drive was marketed as 320gb... I faithfully assumed it would hold close 320gb of compressed data. I have 11 X23 tapes that all have maxed out at 160gb. So i called Tandberg Data. They finally returned my call and assured me that I would never achieve a 320 gb back up as advertised, he actually laughed and agreed that the marketing was false. He claims I am only getting half the capacity (160gb) because I have photoshop files and video files, and to get the full compression (320gb) it would have to be completely text files. Why was this not stated on their websites or literature? Unless your Steven King, this is highly unlikely. My company has sunk over two thousand dollars between the VXA 320 drive, scsi adapter and backup tapes that are only half full when maxed out, how can we be compensated for this false advertising? It is embossed on the machine itself "VXA 320", it should say "VXA 160, unless you have text only files". When you pay for an 8" sub you dont walk out with a 4" sub.

 

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dasystem,

 

You seem to misunderstand basic issues regarding compression technology. It is possible to use the Tandberg (Exabyte) vxatool diagnostic to write 320 GB of data to an X23 tape, if you choose a highly-compressible data pattern and pump the data fast, as that diagnostic is designed to do.

 

Data compression has always been this way. Tape drive data compression has always been this way. Compression technology is not magic. You can't always put ten pounds of s**t in a five pound bag.

 

Why was this not stated on their websites or literature?

It is. You didn't do your homework:

 

Tandberg Compression FAQ

 

If you believe marketing claims, you deserve what you get.

 

What is the point of posting this rant six times today in the Retrospect help forums? Does it make you feel good?

 

Russ

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Hey Russ, you seem to be very emotionally connected with Tandberg Data, I was not trying to offend you, so taking it personally is pretty childish. I'm obviously not an expert on this drive, but if it has the numbers "320GB" embossed on the front case, than obviously getting half that capacity stings a little after spending thousands of dollars on the product. My files are not compressed mpegs or jpgs or zips. They are uncompressed video files and images (quicktime/.psd) which is why I wanted a large backup drive. If I needed to burn text only data I have email for that. You obviously are a master with the VXA, how can I get more than 160GB out of a $60 dollar tape?

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Whatever. If you want to get more data on a VXA tape, you have several choices of which I am aware:

 

(1) use longer tapes;

 

(2) use more compressible data;

 

(3) use the Tandberg / Exabyte vxatool diagnostic to configure your drive to "Prefer capacity" rather than "Prefer speed" optimization;

 

(4) if your hardware / software is not able to pump the data fast enough to the tape drive, the drive will increase the inter-block spacing. Solution there is faster hardware and faster software.

 

I have no partiality for Tandberg products other than to say that our Exabyte VXA drive and its ten-slot autoloader has worked fine for us, and our offsite Retrospect tape backups (one reason to use tape) saved all of our data when our floor of our office building burned down a few years back.

 

Your VXA X23 tapes, just like ours, are rated at 160 GB uncompressed. Anything more than that is a gift from the compression magic.

 

I was just trying to explain the issues to you. These forums are for user-to-user help, not rants.

 

If you don't find my attempts at explanation of the compression issues helpful, then just ignore them and move on with your life.

 

Russ

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Whatever. If you want to get more data on a VXA tape, you have several choices of which I am aware:

 

(1) use longer tapes;

 

Have you found longer tapes than the X23?

 

(2) use more compressible data;

 

How can I make my uncompressed photoshop and video files more compressible?

 

 

(3) use the Tandberg / Exabyte vxatool diagnostic to configure your drive to "Prefer capacity" rather than "Prefer speed" optimization;

 

I've done this already

 

 

(4) if your hardware / software is not able to pump the data fast enough to the tape drive, the drive will increase the inter-block spacing. Solution there is faster hardware and faster software.

 

At the time scsi was the fastest option, so I bought a card for my G5 quadcore, are you saying I would now have to buy another peripheral to meet expectancy? I am using retrospect 6.1.126

 

 

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I am using retrospect 6.1.126

Ok, then this post should not be in the Retrospect 8 forum. Retrospect 6.1 is perfectly capable of keeping a SCSI channel filled on your hardware if you are using an ATTO HBA. Retrospect 8 has a bit of maturing to do. Although it isn't the cause of your present discomfort, you might want to consider updating your copy of Retrospect 6.1 to 6.1.230, which is a year or two newer than the version you are using.

 

Good luck, have a nice day.

 

Russ

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