Avast and Network Copy Performance?

[rbeane]

Olddog...If you have the opportunity, I would be curious if your times changed by copying a large number of smaller files that required checking more files.  I was copying a directory with 30+ 4.5MB pictures instead of single large file.  My thought is that the checking of each file might show similar results to what I was seeing.

[alanrf]

Like olddog my systems are XP (SP3).  Both have avast running on them.

I usually transfer files via drag and drop between directories but today I tried copy and paste.  One odd finding for me suggests at least a peripheral avast involvement.  I choose a 250Mb file and very consistently with avast terminated (on the receiving system) the transfer rate was 78Mbps while with avast running the transfer rate  was 86Mbps.  So it was (repeated the test 5 times with identical results) faster with avast active.  I have no explanation as to why.

[rbeane]

That's weird.  Given that we are trying to determine Avast's scanning involvement with copying, one large file will not be a good test for throughput variation.  Many smaller files will force Avast to cycle through its scanning code multiple times vs. a single time.  Anyone have an opportunity to test multiple medium size files?  Somewhere in the 3-5MB range and 30 or so files.

[alanrf]

Again stressing that this is copy and paste on XP systems not Vista.

On a folder containing 42 files totaling 813Mb copy and paste gave consistent results:

With avast terminated on the receiving system average transfer rate 84Mbps
With avast running on the receiving system average transfer rate 82Mbps

Seems it really awaits someone else with a Vista network to repeat your test. 

[rbeane]

Thanks for trying.  You are right we must wait for a Vista tester.

[olddog]

Stuck@home,

Another test run - same PC's as before but copying 120 files, all .jpg varying from about 1.5MB up to 3.5MB for a total of 265MB. All from one source folder to one existing destination folder, done on a "Select all, copy, paste".

Both PC's rebooted, Avast "All Active protection stopped" on both - Copy/paste took 35.87 seconds.
Files in Destination folder deleted, both PC's rebooted, Avast "All Active protection stopped" on destination PC only - Copy/paste took 37.23 seconds
Files in Destination folder deleted, both PC's rebooted, Avast active on both - Copy/paste took 45.17 seconds.

A further two copy/pastes were then made after deleting the files in the destination folder, but not rebooting either PC, with Avast active on both PC's - Copy/paste took 39.1 and 38 seconds.

Additional observation. On the source PC, after rebooting and with Avast active, the "a" ball was spinning during the the copy paste operation, as was the "a" ball on the destination PC. On subsequent copy/paste's where the source PC was not rebooted, the "a" ball was stationary on the source PC during the operations. Is Avast keeping track of which files have been previously scanned on open?

As before the Standard shields are set to High.

Hope this helps.


 

[Hard_ROCKER]

Interesting i haven't noticed this before but i gave it a shot when i read this thread and copying a 2GB folder full of smaller .jpg files over my LAN network it is quite obvious avast! IS slowing it down. With around 6-7 MB/s with avast! on and after i pause the standard shield it goes over 10MB/s.


EDIT: Forgot to mention i am running Vista 32bit here.

[olddog]

Stuck@home,

In relation to the double scan (scanning of the files on the source PC by the Avast on the destination PC, as well as being scanned again on the destination PC) that you are experiencing, you could try excluding the source PC from being scanned by the destination PC.

In the Standard Shield, Customise, Advanced, enter the source PC path in the form \\SourcePCname\* in the list of locations that will not be scanned.

Could you please try this and let me know whether it makes any difference. 

[rbeane]

Olddog- Now we are getting someplace.    Hopefully devs will notice this thread.

Tests (4) Copy and paste directory with 51 jpgs(2-5MB) totaling 182MB from one networked laptop to another.
1. With Avast standard shield paused on TGT computer =  2.46MB/sec
2. With Avast standard shield active with exclusion for "\\SRCcomp\*" = 2.14MB/sec
3. With Avast standard shield active with no exclusions = 0.99MB/sec
4. With Avast standard shield active with exclusion for "\\SRCcomp\*" = 2.3MB/sec (Same as number 2 to confirm findings)

All tests were done consecutively without rebooting running Avast 4.8.1229 under Vista 32 Ultimate. It looks like the scanning of the src files prior to copying under Vista is slowing down the copy process.  Odd that this doesn't happen under XP.

[olddog]

 Stuck@home,

Well at least that improves the situation.

I noticed during my tests that when I first used Explorer on the destination PC to find and open the folder on the source PC, the files do appear to be scanned as they a displayed on the destination PC screen. It is after this that I started the copy test, using the "select all, then copy" and no further scan occurred at that time. The only scan that occured once the "paste" was issued was to this files being written into the destination folder.

So perhaps what you are referring to is occurring on XP, but at a different time in the process. Again though I am fairly sure the initial scan above only occurs once and not on subsequent runs done without rebooting. I'll try to get some more tests done tomorrow to confirm this and post back the results   

[rbeane]

Interesting on the timing issue.  When I do a copy and paste, I copy the directory so maybe there isn't the opportunity for avast to scan the files prior to copy.  It just seems silly to scan the file on the src then again on the tgt when copying. 

I really don't like the idea of excluding all the files on the remote computer as a solution.  Hopefully the devs will see this and at least respond if that is my only solution.  Thanks for all your help.  This is a great forum because of its contributing members.  I'm sure the developers really appreciate the testing.

I will wait for some comments from Devs.

[igor]

A few notes:

1. It makes quite a big difference what is being copied. In particular, files like JPEG, DOC, XLS are scanned "on open" (when you read them) - most other files are not. So, if you copy this type of files, the source is scanned before the requesting program gets the data.
2. If you already access the source files (which may be e.g. just by opening the folder in Explorer - and Explorer scanning the files to display thumbnails) and avast! scans them, it remembers their status - and unless you modify them, avast! will not scan them again (cause it knows they are clean)
3. You know that you are copying the files - but avast! does not. For avast!, it's just an application (Explorer, for example) reading some files and writing other ones; there's no way to tell if the written data are the same as the read data - they may have been modified by the application, or they may not be related at all.
4. I don't know, however, why JPEG files should be scanned when written - unless either the sensitiviry of the Standard Shield is set to high (specifically, it's configured to scan all created/modified files), or some other application (could be Explorer again, scanning for thumbnails on the target side) is reading them as they are created.

[rbeane]

Igor - For my setup, it is jpg and I am set to normal for standard shield and it is definitely scanning twice when copying a directory.

Interesting on the "already accessed issue", because I copied the same directory from the source computer 4 times without rebooting and the files were not modified at the source, but yet it rescanned them when not excluded.  It does seem that XP is not rescanning them based on other user's post.

[olddog]

Igor,

Thank you for your advice. It explains most of what has occurred during the tests I ran.

You said

.. I don't know, however, why JPEG files should be scanned when written - unless either the sensitiviry of the Standard Shield is set to high

I do have the sensitivity of my Standard Shield set to High - Out of interest I will try the same tests again with it set to Normal

[olddog]

I can now confirm that just as Igor suggested,

If the sensitivity of the Standard Shield is set to High, then the copied .jpg files are scanned when they are written to the destination PC.

If the sensitivity is set to Normal, they are not scanned during the write to the destination PC.