I just have a quick question regarding the amount of storage occupied by the journals. Is there a common ratio to determine how much space will be occupied?
I’m doing very rough map and experimenting with different conditions, but I can’t seem to get a common mechanism for predicting the usable storage limit given the number of locks.
Currently we have an 8 node cluster with 9 journals defined (+1 just in case)… We are awaiting the external storage hardware; but in the time being I am using exporting iscsi drives from another machine to work with.
With 9 locks and creating a 1.75GB partition, I get 655 MB usable from it…. (roughly calculated ratio: 3.37)
With 9 locks and creating a 1.50GB partition, I get 393 MB usable from it…. (roughly calculated ratio: 2.36)
With 9 locks and creating a 1.25GB partition, I get 131 MB usable from it…. (roughly calculated ratio: 0.90)
I’m obviously missing a figure during my calculations because the ratios vary each time… I’d have expected them to be a bit more constant…
At the end of the day I want to be able to know ahead of time how much hard-disk space I need to allocate for ‘X usable’ based on the number of locks I’m using.
The simple equation I used was:
ie: (X/9=.655/1.75 = 3.369)