Why did a Win2k client become so slow to backup?

[xmiinc]

I put this up in the Panther - OSX forum almost a week ago, but never received a reply. Thought I'd try posting here:

 

 

 

I'm using Retrospect 5.1.167 on OSX 10.3.2. Six weeks ago I added a Win2k backup client via TCP/IP over ethernet. At first everything worked fine and up to speed (between 20-30Mb/sec). Now I'm consistently getting 2Mb/sec or less. Looking in my Retro-logs I can pin-point the date at which the dramatic slowdown in backup speed for the client began, but I haven't found the cause or solved the problem. To be clear: Retrospect *is* backing up the client, just very slowly.

 

 

 

The client is a Dell Latitude notebook running a Pentium III, when I do Get Info from Retro, it comes back with just 38k/sec which is about floppy-writing speed, right? I also uninstalled and reinstalled the NIC. Same speed.

 

 

 

The date where slowdowns begin roughly corresponds with my running OSX 'optimizing' packages like 'System Optimizer X 4.1' and 'Onyx'. I'm therefore suspicious that connectivity changes were made to the system that are affecting performance. However, doing generic ping and other network performance monitoring from OSX show no anomalous connectivity speed problems: Ping rates are <23ms on average over a single hop to the client.

 

 

 

Has anyone else had problems with OSX optimizers and Retro backup speeds, or know what system files to check for less-than optimal settings? Is it possible that the client is the source of the slow-down instead of the Retrospect host (OS X)?

 

 

 

thanks!

 

 

[xmiinc]

List moderator(s) - any ideas, suggestions?

[austins]

I am having the same exact problem.

Retrospect 6.0 on a 800 mhz powerpc g4 on os 10.3.2

backing up a Dell Poweredge 1350, Pentium III, running Windows 2000 server.

 

Everything was peachy, until we upgraded from OS 10.2...

which meant we had to upgrade Retrospect from 5.0.238.

 

We are backing up to an AIT-1 tape drive.

 

>100+ MB/sec has lagged to <1 Mb/min.

(I may be exaggerating, but not much).

 

I have searched high (soon low); this is the first time I have seen this problem elsewhere.

 

Please help before the forum goes away.

 

Austin

[xmiinc]

OK, back with a bit of a report:

 

- don't have access to a 2nd Mac, but I did boot into another partition containing OSX and a copy of Retro, did a test backup of Win2k: still slow

- uninstalled/reinstalled NIC, NIC driver, and Retro client: no change in backup speeds...

- examining my system logs I did find this: Mar 7 11:42:56 68-174-9-144 kernel: UniNEnetmonitorLinkStatus - Link is up at 100 Mbps - Half Duplex

 

Shouldn't I be using full duplex?

 

Get Info on the Win2k client currently still shows a piddling 32 - 38k/sec range...but my Retro logs show that at one time I was backing this same client up at speeds between 60 - 70Megs/minute!

 

<sigh>

[natew]

Hi

 

Duplex settings are autonegotiated when the NIC is plugged in. This happens at a much lower layer than Retrospect so I would expect you are seeing a speed hit in other areas as well.

 

Pardon the dumb question but do you get full duplex if you use a different ethernet cable or plug into a different ethernet port?

 

Thanks

Nate

[xmiinc]

Apparently you can't use full duplex unless both systems are config'd as point-to-point ethernet connections, and most hubs don't do full-duplex anyway. In other words, its a specialty service, mostly utilized by servers to clients doing tasks that don't employ a standard req/ack protocol. Most apps are written to employ half-duplex connections.

 

That said, I have no speed hits in any other areas, like browsing, downloading, or FTP. Only Retrospect has slowed down substantially from initially normal transfer speeds. Then, as indicated by my logs, from one backup to the next it slowed down by 80% and now just crawls along at barely 2MB/min. And its been like that ever since.

 

My best guess is that, chronologically speaking, I used a "system optimizer" on OSX around the time of the slow-down. But its just a guess. And frankly, I don't have any idea what to look for in OSX's configuration files that would affect just the transfer rates of one application: Retrospect 5.1.

[natew]

Hi

 

So you are using hubs instead of switches? Switched 100MB will give you full duplex communication. Any chance you can try a switch insetead? Duplex settings are determined at the second or third layer of the OSI model. Depending on your NIC you can also choose to set them manually with from the command line or with an app like cocktail. Retrospect and Retrospect client operate at the top layer(application layer) so it is not aware of the duplex settings on the adapter. The OS should be handling all of that.

 

Retrospect passes standard TCP/IP network calls down to the OS where the actual data transfer is performed. What I am saying is that this is most likely a problem with Networking in general on your machine. It is not uncommon for file sharing and web to work properly while other network communication will fail. I fought similar issues with my powerbook for months until I realized the OSX drivers for my nic were not reliable for anything other than 10Mbit communication. (100MB worked fine in OS9)

 

Can you undo any of the optimizations that were performed on the machine? The most you can do make sure Retrospect's files are valid is to run the uninstaller, reboot the machine and then reinstall.

 

Nate

[xmiinc]

Good points, Natew...

1. there's no way for me to get a hold of a switch without buying one, which doesn't make much sense b/c I don't really need one otherwise. It would only be interesting for testing purposes. Besides, most consumer-oriented switches don't accomodate full-duplex. That said, the hub I'm using (D-link DSH-5) is rated for 100MB thru-put. On the Mac side I haven't done anything re: NIC beyond what can be done with Apple-installed pref panels. Same on the Win2k side. Maybe installing Cocktail could help...?

 

2. I agree with your analysis of specific Network layer failures while other aspects function normally. In my case, there *was* full thru-put happening initially after upgrading to OSX 10.3.2. (Were you using a non-standard NIC with OSX? Surprised to hear anything about a 10Mbit limit on hardware these days...) Unfortunately, without knowing precisely what the optimization changes were, I wouldn't know where to start rolling back those changes.

 

3. Your idea of uninstalling/reinstalling Retro on OSX might be the next best thing to more drastic measures.