On Thu, Feb 23, 2012 at 01:44:35AM +0200, Zeeshan Ali (Khattak) wrote: > On Thu, Feb 23, 2012 at 1:25 AM, Daniel P. Berrange <berrange@xxxxxxxxxx> wrote: > > Yep, the name is about the only difference between them - all the ISO > > metadata is identical. The other thing I considered is to add an MD5 > > checksum of the ISO file, which would trivially distinguish them, > > but I fear that would make it too unique. > > That might be a very good idea actually (Christophe was meaning to do > that any ways?) but calculation of md5 takes a very long time: I wondered out loud if it would be a good idea to have that in the database, that's it :) > so I'll recommend to restrict it to first N bytes, where we could > think/discuss the value of N but 1MiB should be good enough and takes > very little time: Yup, this is what I was thinking too before reading your email. > $ time dd if=~/ISOs/Fedora-16-x86_64-DVD.iso bs=1M count=1 2> /dev/null |md5sum > e25ea147176f24239d38a46f501bd25e - > > real 0m0.011s > user 0m0.004s > sys 0m0.008s > > Actually if we start using md5sum for detection, we can pretty much > remove all other detection logic/extraction. Depends, the other logic will be much faster if for some reason we end up trying to identify remote medias over a slow link. Christophe
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