Oct 282009
 

Seems the PowerBook is the last Unix system that does not have the right uid for myself, but obviously changing uid is totally different from Linux/FreeBSD.

Here is the source and it tells using dscl, and found dscl can do almost all user/group management, and could be more, but I don’t need more :P.

 Posted by at 21:37  Tagged with: ,
Oct 282009
 

I believe I will need to re-install bunch of dev/testing nodes @ home in near future, so I need a online backup service, better be free (I just need it for ~2 weeks), with ~10G space, supporting rsync.

Will dig around to see any luck, what I got earlier is 2G for free, but there is no rsync support.

Oct 282009
 

I don’t think I will have to face hashing algorithms directly as I expect libraries/servers that I’m going to use will provide the best one from their perspective, however, just curious how things are going and also to practice consistent hashing, I wrote a simple perl script.

The result is pretty interesting, I know I cannot cover all test cases, but from various tests I learned:

  • FNV is really a bad candidate for hashing … fnv-1 is worse than fnv-1a
  • CRC32 is not good as expected
  • SHA1 provides acceptable result
  • MD5 is doing pretty good

Performance wise – CRC32 is the winner, MD5 is ~20% slower, SHA1 is ~33% slower. I cannot tell performance of FNV as it is a pure perl implementation while others are Perl module which means results are from C/C++ codes.

This could be my last “research” on consistent hashing, I’m going to move to deployment and try out all those NoSQL solutions.