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Sophos Antivirus and Time Machine

Haravikk

Does anyone else find that the default "Scan This Mac" option gets stuck unless you exclude your Time Machine backup volume from the scan? I was really disappointed with the speed of the scan until I thought to try this, as I was finding it would get stuck about a third of the way in and stay there for hours until I gave up. The only reason I can think of for this though would be if it's scanning the full contents of every backup, but that would be a staggering number of files to get through (my system has millions of files as it is, totalling around 2.5tb).

I would think that an antivirus product for Mac would be aware of Time Machine's file structure and have methods for accelerating the scan. For example, it's pretty easy to figure out which files have changed between two Time Machine backups by comparing inodes, since Time Machine uses hard-links, so only original files and changed files should need to be scanned. Also, since a Time Machine backup is just a snapshot of the rest of your system, it should be easy enough for Sophos antivirus to determine if the file is identical to one already scanned (or waiting to be scanned) on the main system or not, so that copies don't need to be scanned more than once.

Does Sophos antivirus already account for these things? Otherwise I can't figure out why excluding my Time Machine backup would solve the problem. Should I submit a support ticket somewhere?

:1015215


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    kevs40 wrote:

    Thanks Bob, can somene ping someone off! What a cool feature, never heard of that before. Photoshop forums should get that... lot of rude people over there.

    Ok, Sophos suddenly cannot scan time machine volume. What happened, why is this and is there something that can be done or do Mac people have to live with that?

    Hi kevs40,

    I used the word "ping" in the same sense as the word "contact". Just terminology I use regularly, in my case it originates from the network activity resulting from the "ping" command line tool. That tool sends out small packets on the network to test reachability.  http://en.wikipedia.org/wiki/Ping_(networking_utility)

    The scanner can scan Time Machine volumes however it will likely be quite slow; we don't attempt to optimize scanning identical files - we simply scan each and every copy of every file for every backup as if it was a unique entry. Earlier in this thread it was suggested that we could do better. I agree, but its not at the top of our priority list. Note that we do have issues cleaning up anything found in the Time Machine volume - again this is something we could improve.

    Recommendation is to add an exclusion to your on-demand / scheduled scan to not scan your Time Machine backup volume. You can double-click or right-click the "Scan This Mac" panel to get access to its settings.

    :1020232

    ---

    Bob Cook (bob.cook@sophos.com) Director, Software Development

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  • 0
    kevs40 wrote:

    Thanks Bob, can somene ping someone off! What a cool feature, never heard of that before. Photoshop forums should get that... lot of rude people over there.

    Ok, Sophos suddenly cannot scan time machine volume. What happened, why is this and is there something that can be done or do Mac people have to live with that?

    Hi kevs40,

    I used the word "ping" in the same sense as the word "contact". Just terminology I use regularly, in my case it originates from the network activity resulting from the "ping" command line tool. That tool sends out small packets on the network to test reachability.  http://en.wikipedia.org/wiki/Ping_(networking_utility)

    The scanner can scan Time Machine volumes however it will likely be quite slow; we don't attempt to optimize scanning identical files - we simply scan each and every copy of every file for every backup as if it was a unique entry. Earlier in this thread it was suggested that we could do better. I agree, but its not at the top of our priority list. Note that we do have issues cleaning up anything found in the Time Machine volume - again this is something we could improve.

    Recommendation is to add an exclusion to your on-demand / scheduled scan to not scan your Time Machine backup volume. You can double-click or right-click the "Scan This Mac" panel to get access to its settings.

    :1020232

    ---

    Bob Cook (bob.cook@sophos.com) Director, Software Development

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