* the 1st data chunk(8M) allocated by mkfs.btrfs can not be allocated again after full balance?
@ 2022-08-07 1:19 Wang Yugui
2022-08-07 1:24 ` Qu Wenruo
0 siblings, 1 reply; 2+ messages in thread
From: Wang Yugui @ 2022-08-07 1:19 UTC (permalink / raw)
To: linux-btrfs
Hi,
The 1st data chunk allocated by mkfs.btrfs is 8M. After full balance,
this 8M chunk is freed, and new allocated chunk size
is changed to 1G.
Then this 8M space can't be allocated again?
Or we should allocate 1G for 1st data chunk in mkfs.btrfs?
Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2022/08/07
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: the 1st data chunk(8M) allocated by mkfs.btrfs can not be allocated again after full balance?
2022-08-07 1:19 the 1st data chunk(8M) allocated by mkfs.btrfs can not be allocated again after full balance? Wang Yugui
@ 2022-08-07 1:24 ` Qu Wenruo
0 siblings, 0 replies; 2+ messages in thread
From: Qu Wenruo @ 2022-08-07 1:24 UTC (permalink / raw)
To: Wang Yugui, linux-btrfs
On 2022/8/7 09:19, Wang Yugui wrote:
> Hi,
>
> The 1st data chunk allocated by mkfs.btrfs is 8M. After full balance,
> this 8M chunk is freed, and new allocated chunk size
> is changed to 1G.
>
> Then this 8M space can't be allocated again?
It can, but needs very complex relcation, e.g. relocate all chunks to
other devices (e.g. delete the device and add back).
Or run very low on unallocated space.
The reason why it can not be really utilized is, chunk allocator will
always use the largest unallocated range by default.
Thus such small 8M will not be utilized until no more free space.
> Or we should allocate 1G for 1st data chunk in mkfs.btrfs?
I think we should follow kernel allocation size, but I'm not confident
on small devices.
Thanks,
Qu
>
> Best Regards
> Wang Yugui (wangyugui@e16-tech.com)
> 2022/08/07
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-08-07 1:19 the 1st data chunk(8M) allocated by mkfs.btrfs can not be allocated again after full balance? Wang Yugui
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