[PLUG] Faster giant disk copy

Don Buchholz buchholz at easystreet.com
Tue Aug 17 08:23:01 UTC 2004


Keith Lofstrom wrote:

>I wrote, asking about copying a big disk with enormous numbers of
>hard links to another drive.  Some suggested tar, others suggested
>rsync.  I have not run Russell's example yet, but I did pick a medium
>sized directory with 119 hard links and copied them three different
>ways.  The results are:
>
>               real       system
>rsync -a:      37m 30s     2m 40s    // Not Russell's approach
>piped tar:     18m 10s        26s
>cp -a:         17m 22s        25s
>
>I will investigate Russell's approach and see if that gives a speed
>boost.  However, I suspect that this will be pig slow unless the
>process knows what kind of structure it is processing, hence the need
>for a magic program of some sort.  For now, I guess I will just leave
>the damned thing running for a few more days.
>  
>
This is probably coming too late, but, IIRC, dump/restore scales very nicely
with disk size and has little problem with many, many inodes.  Of 
course, the
downside to dump is that it is safe only when the filesystem is 
unmounted (or
mounted read-only).





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