"System has insufficient buffers to rebalance the tree." after upgrade to 3.8.1

Marco Righele marco at righele.it
Sat Jun 28 11:30:30 PDT 2014

On 2014-06-27 18:34, Matthew Dillon wrote:
> The hammer rebalancing implementation needs a lot of buffer cache
> buffers, the system doesn't reserve enough in smaller memory
> configurations.  The buffer cache was retooled since 3.6 and the
> calculations have changed enough that 2GB of ram doesn't get it past
> the minimum for rebalancing.
> However, you don't have to worry about it.  The rebalancing is not
> that big a deal.

Thanks for the answer.
I'd suggest to update the man page and/or the program output then.
The "No space left on the device" message in particular put me
off track.

> Unrelated to balancing, you do have to be careful about free space.
> 10% is getting dangerous so you might have to reduce the nominal
> history retention (hammer viconfig <partition>) from 60 days to
> something smaller.  When hammer1 runs out of space it sometimes takes
> wiping the whole snapshot history and doing piecemeal reblockings to
> get it back into good shape.

This is something I already learned the hard way :-), thanks for the 
heads-up anyway.


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