When downloading a large file with the ISA provider enabled, the download ends abruptly, resulting in a truncated file. This problem happens repeatedly.
However, as soon as I disable the ISA provider, the download completes normally.
The problem happened most recently with the 160-MB download of WSUS SP1 from this page:
http://www.microsoft.com/windowsserversystem/updateservices/downloads/WSUSSP1.mspx#EHC
Ken
Hi again kwg,
Is this ISA 2K or 2K4? Has this happened in the past?
Thanks
Vlk
Hi, Vlk,
It’s ISA 2004.
It hadn’t happened before last night, but I had not recently download files as large as 160 MB.
Ken
How long is the truncated file, exactly? And is it always truncated at precisely the same length?
The size of the truncated file varies with each download. For example, I just attempted twice the download of the 160-MB file mentioned above. The sizes of the truncated files were
10,854,791 bytes (10.45 MB)
107,485,151 bytes (102.51 MB)
Ken
Please check free disk space on the ISA server computer, especially on the system partition.
Thanks
Vlk
The system partition has 2 GB of free space. The data partition (to which the file was being downloaded) has 330 GB of free space.
Ken
2GB? I wonder if this number fluctuates. I mean, is it possible that at times, it gets very low?
I’m asking because avast is storing the temporary data (downloads in progress) in temp files, of course.
Also, it would be interesting to find out if the problem happens only with the link above, or any other large download (try downloading e.g. some ISO images from
http://cudlug.cudenver.edu/debian-cd/3.1_r1/i386/iso-cd/ (or any other site hosting big stuff))
Thanks
Vlk
Yes, the truncation of files does occur with other large downloads. For example, I just attempted to download a 645-MB .iso file from cudenver.edu. The downloaded file was truncated at 82 MB.
I monitored the free space on the system partition during the download. Free space fell gradually during the download, but never below 2.0 GB.
After the download, this error appeared in the Avast logs:
[SBS2003]: AAVM - scanning error: x_AavmCheckFileDirectEx: avfilesScanReal of http://cudlug.cudenver.edu/debian-cd/3.1_r1/i386/iso-cd/debian-31r1-i386-binary-10.iso failed, 00000084.
Ken
I’m not sure if this is applicable with the avast4 server edition, but if that 00000084 error number is a windows error ‘Storage to process this request is not available.’ Which seems strange based on your free space info.
If the 00000084 error code was logged only during the download of this ISO file, I don’t really think it’s relevant to this problem. Rather, it’s the avast ISO unpacker that’s complaining that the ISO files is in fact corrupt (in this case, truncated).
BTW Did you try restarting the Web Proxy service?
As another test, I restarted the Web Proxy Service and immediately attempted a download of this 37.9-MB file:
http://mirrors.isc.org/pub/openoffice/stable/2.0.3_sdk/OOo_2.0.3_LinuxIntel_sdk.sh
Once again, the downloaded file was truncated, this time at 17.4 MB. The free space on the system partition never fell below 2.1 GB during the download.
Then I disabled the Avast MS Proxy/ISA provider and downloaded the same file. This time, all 37.9 MB were downloaded without truncation.
So the problem continues and is certainly related to the Avast MS Proxy/ISA provider.
Ken
One more question: is it enough to pause the ISA provider?
And one more thing: could you please try, for a while, change the logging level of the ISA provider to “Maximum” and simulate the problem? (turn it back to Normal when you’re done, otherwise the logs will be flooded with data :))
When you’re done, send me the logs.
Thanks
Vlk
With the ISA provider paused, the downloaded file is still truncated.
It necessary actually to stop the ISA provider in order to download a large file without truncation.
I’ll generate some logs later today.
Ken
Well, the problem (for now) has gone away! 
It went away as soon as I set the logging to Maximum and saved the new configuration. Even with logging set again to Normal, the problem has not returned.
Perhaps the ISA provider’s configuration had become corrupted (perhaps with the recent upgrade to Avast 4.7). Saving the new configuration (with logging) might have repaired the corruption.
If the problem returns, I’ll let you know and also generate some logs.
Ken
Hmm, interesting indeed… :
Thanks
Vlk