Very slow backup over ethernet

[twickland]

How do I avoid the file time stamping issue I've seen talked about in the forum? Does this cross OS time stamping issue render using Retrospect with a non windows OS NAS basically useless?

Are you referring to the different way that Windows and Macs handle the DST/Standard Time changes? This, of course, only happens at the twice-yearly time change intervals, and only when the source computer and the backup computer are running different OSes. Under these circumstances, Retrospect sees all files on the source computer as having changed because their creation and modification dates seem to have shifted by one hour, and will back up everything again.

 

In an all-MacOS (or all-Windows) setup, this issue won't occur.

[ttigner]

First of all, thank you to the numerous responses to my questions regarding performance posted on Sunday evening.

 

I am encouraged to see the activity on this forum not only in terms of the presense of valuable help - but it is also an indiation of the vitality of this community - and then also of Retrospect. Good signs!

 

You guys have addressed several of my issues - I still just need to figure out HOW to get better throughput via my cat 5 ethernet MacBook Air adapter hooking up directly to a Gigabyte netork and what is reported as a fast NAS.... Yikes. Thoughts on this still VERY welcomed!!

 

 

To dukebedford:

a. Clarification: the 26MB/min was the result with a hard wired ethernnet connection - not wireless. But I note that the USB/Ethernet Cat 5 adapter is limited to 100mbps not 1000. So I didn't know if this was constraining this throughput down to the 26 or not.

b. Good input on the first backup and subsequent incrementals, and the limitations with Time Machine. Perhaps I made the right move afterall...

 

To Russ:

a. Performance: I hope the issue is not the NAS. It is rated among the top at smallnetbuilders - one reason why I picked it.

b. The Timestamp Problem: This is claimed to be causing verificaiton errors. I'm referring to the dialog happening on the Netgear ReadyNAS forum where they are quoting Tech Support from EMC. I don't fully understand the issues, but when the thread is read by a new user - it appears that there may be a real issue here. How would you translate this issue?

http://www.readynas.com/forum/viewtopic.php?f=4&t=19921

 

To CallMeDave:

a. Defining the backup set: actually when a new set is defined, you have to click on NEW in order to bring up the "destination" dialog. If you don't click on new then there is no opportunity presented to specify location before the backup is started. With this approach I wasn't able to find the location where the set was being placed. It, of course, didn't default to the NAS - and with the high throughput I just assumed it is somewhere on the local drive.

b. Thanks for the reassurance on the other issues. I am encouraged to continue - I just need to allow for the first backup to be a 24 hour period unless I can speed the throughput somehow. Sure seems like I should get better than 26MB/min....

 

To twickland:

Time Stamp: Again, just picked up the thread from Netgear ReadyNAS forum and it created concerns (link above).

 

Thanks again, guys! I just need to figure out when to schedule that first 24 period unless I can get better speed out of this situation.

 

Terry

 

 

 

 

[rhwalker]

To Russ:

a. Performance: I hope the issue is not the NAS. It is rated among the top at smallnetbuilders - one reason why I picked it.

b. The Timestamp Problem: This is claimed to be causing verificaiton errors. I'm referring to the dialog happening on the Netgear ReadyNAS forum where they are quoting Tech Support from EMC. I don't fully understand the issues, but when the thread is read by a new user - it appears that there may be a real issue here. How would you translate this issue?

http://www.readynas.com/forum/viewtopic.php?f=4&t=19921

I hadn't previously seen this Netgear thread, but, upon studying it, it is NOT discussing backups, but instead is discussing DUPLICATE copying. See this Retrospect support document on the difference:

What is the difference between "Backup" and "Duplicate"?

 

The underlying problem is that the NAS's filesystem does not support all of the metadata needed by the Macintosh filesystem. Perhaps it's an issue that the timestamp is not of the same granularity, perhaps the same permissions model is not supported, whatever.

 

A "duplicate", which this thread is referencing, is a simple "file copy". I would expect such a copy to preserve on the destination file all of the metadata present on the source file. If the destination filesystem can't do that, well, Retrospect's verification check is reporting that fact correctly. You would see the same lack of matching of source and destination if you used the Finder's copy operation, and then compared the metadata at source and destination.

 

To my thinking, Retrospect is doing the right thing, telling you that the file copy it has made didn't end up with the right stuff. You may not care that it's not right, but I do.

 

Here are the possible solutions:

 

(1) get the NAS to upgrade its filesystem support. Unlikely to happen.

 

(2) make it look like the NAS has a Macintosh filesystem - create a "sparseimage" disk image on the NAS using Disk Utility, then share that sparseimage and mount it on the Retrospect machine, and Retrospect will see a Macintosh file system inside that disk image.

 

(3) Use a Macintosh filesystem for the destination.

 

(4) don't do a duplicate, but instead do a "backup", with the backup set on the NAS. Retrospect will store the metadata correctly inside of the backup set, because that's Retrospect's own container.

 

If you really want to do the "duplicate" (copying) operation, there are better tools for that (e.g., SuperDuper!, Carbon Copy Cloner, etc.). Retrospect's strength is backup and restore, not copying (duplication / syncing).

 

Russ

Edited December 16, 2008 by Guest

[ttigner]

Russ,

 

Thanks for the explanation. The fact that this issue isn't related to the backup process resolves a big question for me. At the end of the day your explanation makes perfect sense.

 

I think I've been a little surprised and therefore leary by how far behind (it seems to me) that the mainstream (enthusiast & home) Mac market is in having a broad array of tools and practices for backup. And so I wondered if this issue was another indication of immaturity. Now I'm starting to "get" how Retrospect stands in contrast to the rest.

 

Just wish I could fix that throughput issue....

 

Thanks again for taking the time.

 

Terry

[ttigner]

Throughput improvement.

 

Previous: 26MB/min.

Current: 117MB/min.

 

Not sure what all might have contributed - but the explicit, intentional change was to hang both the Macbook Air USB-Ethernet Adapter directly off of the DLink DIR-655 router along with the Netgear ReadyNAS.

 

Previously I had the Macbook Air USB-Ethernet Adapter routed through a DLink Gigabit Ethernet Switch which hangs off of the DIR-655. (The NAS was always right off of the 655.)

 

I rerouted to to eliminate the switch. I also deleted and created a new Backup Set on the NAS and restarted the backup - planning on 24+ hours with 40GB+ of files on the Mac. But now it is reporting 117MB/min. and I am not compaining!!

 

This should complete overnight (6+ hours).

 

Nice improvement!