[Linux-cluster] GFS & journal resources ... common ratio?

[Kevin Anderson]

On Tue, 2008-10-07 at 16:57 -0400, Caron, Chris wrote:
> 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?
> 

Default Journal size is 128MB.

> 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.

9 * 128MB = 1152MB - which is pretty consistent with your remaining
space below.

> 
>  
> 
> 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:
> 
> X/9=USABLE/ALLOCATED
> 
>  
> 
> ie: (X/9=.655/1.75 = 3.369)
> 
>  
> 
>  
> 
> Chris
> 
> 
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster