Urgently need some help solving lost space due to snapshots during receive op

[Da Rock]

On 10/08/2015 18:42, Willem Jan Withagen wrote:
> On 10-8-2015 06:42, Da Rock wrote:
>> I'm trying to move a pool from one system to another - exact same hdd
>> and config, different in other areas. Both register same space
>> available, and so should be no issue. The old system is quite full -
>> still at least 5% free though.
> Hi,
>
> Are the versions of your FreeBSD also equal?
No. 9.1 to 10.1.
>
> Because in newer version, the free space reservation is significantly
> bigger. So if disks are equal size, then with newer FreeBSDs you have
> less usable space available.
> Don't know the exact SVN commit where it happened. But there are more
> question on this topic in the list, and they all boil down to the same
> thing: ZFS needs more reserved space to be able to do certain things
> without freezing the system.
>
> I've not read any suggestions that you can circumvent this setting.
Crap. So I guess my best will be to compress as best I can for the 
moment or something like that.
>
> As a second note I think is is more or less general understanding that a
> ZFS systeem needs a lot more space left free than 5% to actual be able
> to perform.
> Last number I remember as sensible maximum fill level is around 70%.
> If you go over it, your system is going to be busy with ZFS bookkeeping
> instead of data storage.
Yeah, I noticed that. Something I'm working on... backlog of sorting 
activities really :) Once I'm done it'll drop to well below 50% I'd say.
> (One of the things I remember from the ZFS lecture by Kirk McKusik,
> which I no longer can find on YouTube :( )
>
> --WjW
Thanks for the info - I owe you a beer! At least I know why now and 
eases my growing headache from banging my head on the brick wall.
>
>> I have done a recursive snapshot on the system and a send/receive over
>> ssh. Near the end, it final croaks and says no space left. The snapshot
>> it is sending is nowhere to be found on the receiving system.
>>
>> Ok, checked free space - should be enough - so I try a simple cp op on
>> the last dataset, but then it again croaks no space near the end, but at
>> least I have some data.
>>
>> Checking space again, it says free space of an expected value, but still
>> won't allow further data.
>>
>> I can't seem to figure out why this is not working, I'm currently trying
>> using compression on the dataset to see if it can't squeeze it on there,
>> but I still have a couple of no space messages so far.
>>
>> Where has my space gone?!
>>
>> TIA
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