Brad Fitzpatrick (brad) wrote,
Brad Fitzpatrick
brad

MogileFS is fun

We keep making a bunch of new monitoring and admin tools for MogileFS.

This is a cute little command-line one to show all the known hosts and devices. In addition to "sto1" and "sto2" shown below, we now have 8 new machines each with 4 hot-swap SATA bays, and 3 or 4 others with 2 hot-swap SATA. If we ever fill up our 6.1 TB free we can easily expand. We'll probably be adding a third host soon anyway, just so we can upgrade the file classes to have "min_replicas" of 3 instead of 2.

Currently MogileFS never makes replicas on devices on the same machine, because doing the indexes efficiently is too big/slow that way. The danger is that if you have 3 replicas, but split up with 2 on host_A and 1 on host_B, what happens if you lose that device on host_B? Now the replica count is down to 2, but it's not a "safe" 2, because both are on the same host. So we avoid hurting our brain about that and say that our per-file "devcount" value is always "devcount on different hosts".

lj@grimace:~$ mogcheck.pl
Checking mogilefsd availability...
        10.0.0.81:7001 ... responding.
        10.0.0.82:7001 ... responding.

Device information...
  hostname     device   age    size(G)       used       free    use%  delay
      sto1       dev1    7s    224.319     14.930    209.389   6.66% 0.005s
      sto1       dev2    7s    229.161      9.248    219.912   4.04% 0.004s
      sto1       dev3    7s    229.161      9.178    219.983   4.01% 0.004s
      sto1       dev4    7s    229.161      9.224    219.936   4.03% 0.004s
      sto1       dev5    7s    229.161      9.182    219.979   4.01% 0.004s
      sto1       dev6    7s    229.161      9.314    219.847   4.06% 0.076s
      sto1       dev7    7s    229.161      9.203    219.958   4.02% 0.026s
      sto1       dev8    7s    229.161      9.242    219.919   4.03% 0.004s
      sto1       dev9    7s    229.161      9.212    219.948   4.02% 0.051s
      sto1      dev10    7s    229.161      9.156    220.004   4.00% 0.117s
      sto1      dev11    7s    229.161      9.254    219.907   4.04% 0.019s
      sto1      dev12    7s    229.161      9.194    219.967   4.01% 0.004s
      sto1      dev13    7s    229.161      9.273    219.887   4.05% 0.005s
      sto1      dev14    7s    229.161      9.191    219.970   4.01% 0.004s
      sto2      dev15   41s    224.319      9.254    215.065   4.13% 0.005s
      sto2      dev16   41s    229.161      9.230    219.930   4.03% 0.006s
      sto2      dev17   41s    229.161      9.287    219.874   4.05% 0.004s
      sto2      dev18   41s    229.161      9.292    219.868   4.05% 0.008s
      sto2      dev19   41s    229.161      9.142    220.019   3.99% 0.005s
      sto2      dev20   41s    229.161      9.232    219.929   4.03% 0.004s
      sto2      dev21   41s    229.161      9.109    220.052   3.97% 0.004s
      sto2      dev22   41s    229.161      9.221    219.940   4.02% 0.016s
      sto2      dev23   41s    229.161      9.133    220.028   3.99% 0.018s
      sto2      dev24   41s    229.161      9.277    219.884   4.05% 0.004s
      sto2      dev25   41s    229.161      9.220    219.941   4.02% 0.004s
      sto2      dev26   41s    229.161      9.165    219.995   4.00% 0.004s
      sto2      dev27   41s    229.161      9.183    219.978   4.01% 0.008s
      sto2      dev28   41s    229.161      9.226    219.934   4.03% 0.020s
                total         6406.817    263.774   6143.043   4.12% 0.437s


MogileFS needs better docs.
Tags: perl, tech
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