Corrupted Archives

[deed02392]

Part of how I use my subscription is to download archives created by a server I lease. These large backup archives are sensitive to the quality of the network. It seems for the last several weeks I've been unable to succesfully download these archives, as they continually download corrupted.


I have investigated this on my own LAN, including connecting directly to the modem, testing several different computers on different operating systems. Never do the archives download intact to sufficiently archive. I have asked for advice from an IT professional who first suggested it would be my Internet connection as the cause, but regardless I chose to invest my own time in testing my equipment first.


It seems however I have reached the conclusion it is either a fault with the network or my modem. What action do I take from here? Please advise.


Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 24
Downstream Frequency : 322750000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 6952 Ksym/sec
Downstream Interleave Depth : taps12Increment17
Downstream Receive Power Level : 7.9 dBmV
Downstream SNR : 40.5 dB

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 5
Upstream Frequency : 42800000 Hz
Upstream Modulation : QAM16
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 54.0 dBmV
Upstream Mini-Slot Size : 2

[gazfan]

Have you tried saving the files as 'rar' archives with an appropriate % of 'par' files to help manage corrupted downloads?

[deed02392]

They aren't RAR archives. They are tar balls compressed with gzip.

[gazfan]

They aren't RAR archives. They are tar balls compressed with gzip.


- I'm not familiar with Gzip - is there a similar redundancy structure to PAR files available?

[deed02392]

I am not sure but I won't be finding out - adding redundancy to the files by adding a recovery record will increase their size and judging by the amount of corruption in the current archives I'm getting, will not be enough.

Someone put it to me that perhaps it is the weather affecting power levels on the network, thus affecting the reliability of downloads. Could this be a factor?

[gazfan]

I am not sure but I won't be finding out - adding redundancy to the files by adding a recovery record will increase their size and judging by the amount of corruption in the current archives I'm getting, will not be enough.

your choice - afaik you can choose the % of par files generated based on anticipated corruption, but only you can decide if file size is more important than data integrity.

Someone put it to me that perhaps it is the weather affecting power levels on the network, thus affecting the reliability of downloads. Could this be a factor?

no idea - you would need to contact your host/data centre in the first instance, if they have no problems then something as simple as an overheating local junction box could be a problem - but you'll need an engineer out to investigate that :)

[deed02392]

Not so much 'overheating' as it just being a trivial thing that causes minute changes in power levels on your modem. It would be quite interesting to log power levels with nominal temperatures from the weather report to see if there is any reality in this...