Backup Client Suddenly Slow

[stevefoobar]

I've had Retrospect for years. Normally my local computer backs up files at around 700 mbps. My single client over my local network normally backs up at around 400 mbps.

 

It seems like starting a few months ago, my local backup speed hasn't changed but my client backup speed has dropped to around 150 mbps. At this speed it takes multiple days to fully back the computer up.

 

I don't understand what has happened. I don't remember changing anything on the network, the router, or anything else for that matter.

 

The remote client is a Wi-Fi N client but it always has been and always has a strong signal and maximum Wireless N speeds so that hasn't changed.

 

I would appreciate any ideas.

 

Thanks.

[David W Lee]

For quickly checking the baseline performance, you can try uncompressed backup to a new backup set from a subvolume containing very small number of large files, say 2 GB each, while turning off verification. If that is closer to the faster backup speed you used to see, the more recent slow down may be due to larger number of smaller files which take longer to back up. If the baseline test yields similar speed as your recent slower backups, then the slow down may be due to environmental factors: e.g. Internet security software/hardware, WiFi signal interference, etc.

 

Another consideration is whether the still-fast local backup and now-slower client backup use the same backup set, or at least different backup sets on the same disk volume, for narrowing down cause(s) of slower backup.

[stevefoobar]

Thanks David. I have done this and is appears it has nothing to do with the number or size of files but rather environmental as you suggested. Both backups (local and client) use different backup sets (identical in how they are configured though) but the same hard drive so those aren't variables. Narrowing it down further from this point would probably be rather difficult.

[stevefoobar]

I am still getting extremely slow speeds that cause this client to take two full days to back up the first time! There are some things that I didn't mention in the original post that could be a clue to what's going on.

 

Most notably that this client used to be a completely different computer running Windows XP Pro when the backup speeds were very fast (around 400 mbps).

 

It now seems like the slower speeds started after this computer was switched our for a new computer running Windows 7 64-bit.

 

Both the old computer (Windows XP Pro) and the new computer (Windows 7) are using a similar Wi-Fi N connection and it's very stable with a solid consistent speed of 150 mbps, which is actually faster than my wired ethernet network (100 mbps) so I highly doubt the problem has anything to do with the Wi-Fi connection, especially since both the old and new computers had a similar connection.

 

Of course, the client app is configured for maximum priority to the bacups but that still doesn't seem to be helping with the speed.

 

I'm now assuming it must be something to do with either the hardware or OS change.

 

Any ideas would be appreciated.

 

Thanks.

[stevefoobar]

The backup of the client computer finally finished and there is some important detail to add to this problem.

 

I noticed that although the previous backups of this client were at about the same "slow" speed of around 120 mbps, the backups normally take about 6 hours for the first backup. This time, although the average backup speed was the same 120 mbps, THE FIRST BACKUP TOOK 103 HOURS!

[David W Lee]

I see your support ticket, and will follow up with Support regarding the on-going communications.

[stevefoobar]

Thanks David. I told the tech that I would try and move the client computer closer to the router and connect it directly via Ethernet to see what speeds it gets than to rule out anything odd with the Wireless connection and hardward, however, the person uses their computer almost 20 hours a day and at very odd hours so it's very difficult for me to snatch it away for this test.

[Scillonian]

The remote client is a Wi-Fi N client but it always has been and always has a strong signal and maximum Wireless N speeds so that hasn't changed.

 

Is the remote client using the 2.4GHz or 5GHz band for the Wireless 'N' connection? Although the old and new clients are both using Wireless 'N' they could be doing so in different bands.

 

Both the old computer (Windows XP Pro) and the new computer (Windows 7) are using a similar Wi-Fi N connection and it's very stable with a solid consistent speed of 150 mbps, which is actually faster than my wired ethernet network (100 mbps) so I highly doubt the problem has anything to do with the Wi-Fi connection, especially since both the old and new computers had a similar connection.

 

Have you been able to see what the connection speed is on the client when it is in use by Retrospect? I have had many experiences of WiFi connections where at idle the show a nice high connection speed but immediately they are put under heavy load the connection speed drops dramatically.

 

This is another reason why a test using a wired Ethernet connection to the client would be useful to get a baseline speed and rule one way or the other whether the problem lies with Retrospect or the WiFi hardware.

 

Also, do you have any USB3 devices connected to the new client or in use near the WiFi Access Point? Some research by Intel shows that USB3 can interfere with WiFi in the 2.4GHz band. (http://www.usb.org/developers/whitepapers/327216.pdf)

 

 

[stevefoobar]

Scillonian, good questions. The router I'm using currently only transmits on Wireless-N at 2.4 GHz. I believe the old computer was also using Wireless-N at 2.4 GHz.

 

Since the backups on the cient start at 4:00 AM I have not watched the wireless speed while backups are in progress but that may be a good test to see if the 150 Mbps speed drops.

 

There are currently no USB3 devices connected to the client machine or near the access point. I'll have to read the article--sounds interesting.

 

I finally was able to snatch the client computer and I'm testing it right now with a direct connection. I'll also be running some other tests related to the proximity to the access point so I'll post the results when I'm done.

 

Thanks.

[stevefoobar]

Tests 1, 2, and 3 were done with the client computer moved directly next to the wireless router. Test 4 was done with the client in its normal location about 20-25 from the router on the upper floor of the house. I don’t know what the unit of measure is for the Retro Performance numbers since I can’t find that information in the Help file. Wireless-N Device 1 is built into the client computer motherboard with no external antennas. Wireless-N Device 2 is a PCI-Express card with two external antennas. I included the backup speed of the host computer to a local USB drive as a baseline.

 

Another thing I noticed is that there doesn't seem to be a strong correlation to the reported Retro Client Speed and the Retro Performance except in the obvious case of an Ethernet connection. Also, every time I refreshed the client on the General tab within the client properties box while connected wirelessly, I got a different value for Speed, sometimes varying as much as between 2.0 MBps and 3.6 MBps.

 

Since I couldn't seem to insert a table in this editor, I've attached a PDF file containing the results.

Tests.pdf