lastlog devours universe

Neal Becker ndbecker2 at gmail.com
Wed Jun 8 11:09:53 UTC 2005


Jesse Keating wrote:

> On Tue, 2005-06-07 at 16:35 -0700, Andy Ross wrote:
>> Indeed:
>> 
>>   tar cf /tmp/unbelievably-huge-file /var/log/lastlog
>> 
>> I killed it after 10 seconds and a few hundred MB.  What if someone
>> tries to backup their logs?  Surely there must be a saner way to store
>> this data than a 1.2TB sparse file...  This is a sysadmin disaster
>> waiting to happen.
> 
> From 'man tar'
> 
>        -S, --sparse
>               handle sparse files efficiently
> 
> 
> From 'man rsync'
> 
>         -S, --sparse                handle sparse files efficiently
> 
> Most backup software I've looked at mentions sparse files and how to
> handle them.  Perhaps what is prudent is a mention in the release notes
> and FAQs that /var/log/lastlog is a sparse file and should be treated
> accordingly.
> 

If the change that causes /var/log/lastlog to be a huge sparse file is
accepted, it is _imperative_ that all common backup tools be updated to
support sparse by default.  Actually, I don't understand why this isn't the
default anyway, except that it is a tiny bit slower (on Linux systems it
shouldn't be significantly slower).




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