[Gluster-users] behavior of ALU Scheduler

Deian Chepishev dchepishev at nexbrod.com
Tue Oct 21 11:57:31 UTC 2008


I have one question about the ALU scheduler.

If for example I have one UNIFY volume which is using ALU scheduler with 
the following config:

volume unify
 type cluster/unify
 option namespace afr-ns
 option scheduler rr
  option scheduler alu   # use the ALU scheduler
  option alu.limits.min-free-disk  3%      # Don't create files one a 
volume with less than 5% free diskspace
  option alu.limits.max-open-files 10000   # Don't create files on a 
volume with more than 10000 files open
  option alu.order 
  option alu.disk-usage.entry-threshold 300GB   # Kick in if the 
discrepancy in disk-usage between volumes is more than 2GB
  option alu.disk-usage.exit-threshold  100GB   # Don't stop writing to 
the least-used volume until the discrepancy is 1988MB
  option alu.open-files-usage.entry-threshold 1024   # Kick in if the 
discrepancy in open files is 1024
  option alu.open-files-usage.exit-threshold 32   # Don't stop until 992 
files have been written the least-used volume
  option alu.stat-refresh.interval 10sec   # Refresh the statistics used 
for decision-making every 10 seconds
subvolumes brick1-stor01 brick1-stor02

And I have the following directory structure visible from the client:



In directory test1 I have for example files: testfile1.dat and 
testfile2.dat which are physically located respectively
testfile1.dat on stor01
testfile2.dat on stor02

If the space on the bricks is such that ALU scheduler is in active 
state, in this particular example if the free space difference is more 
than 300G and stor02 have more free space than stor01

what will happen if I execute the following command? :

mv /mnt/gfs/test1/*  /mnt/gfs/test2

Is it going to physically move the files from stor01 to stor02 or it 
will leave it on the same server and just do a local filesystem move 
than copying the files over the network?


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