Re: simple Chunk allocator like calculation to replace Factor based calculation

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,


> > such as
> > 1) RAID10 with 8T,1T,1T,1T,1T
> >     the virtal chunk size of 1st iteration:	1T or 0.33T?
> >     1T    chunk will use 4T at most
> >     0.33T chunk will use 5.33T at most?
> 
> You didn't get the point.
> For the each loop we:
> - Sort the devices with their free space.
>   In this case, it's 8, 1, 1, 1, 1.
> 
> - Round down to dev increament
>   Then we got 8, 1, 1, 1.
> 
> - Then allocate chunk
>   Since the biggest unallocated space is 1T, we allocate a RAID10 with
>   1T stripe size, which will be a 2T chunk.
> 
>   The remaining size is 7, 0, 0, 0, 1.

That is the problem.  1T chunk size is too big for this case.

if we use 1/3T chunk size, the result will be same as 1G chunk size.

1st:	8T - 1/3T     2/3T, 2/3T, 2/3T, 1T
2nd:	8T -2/3T     2/3T, 1/3T, 1/3T, 2/3T
3rd:	8T -1T        1/3T, 1/3T, 0T, 1/3T
4th:	8T -4/3T     0T,     0T,   0T,  0T

Best Regards
王玉贵
2020/10/02

> 
> - We go to next round.
>   No way to allocate new chunk.
> 
> In this case, we can only get 2T chunk.
> Just as the chunk allocator do.
> 
> > 
> > 2) RAID10 with 8T,1T,1T,1T,0.5T
> >     the virtal chunk size of 1st iteration:0.5T or smaller?
> 
> Still the same, 2T chunk can be allocated using the largest 4 devices.
> 
> Thanks,
> Qu
> 
> > 
> > Best Regards
> > 王玉贵
> > 2020/10/02
> > 
> > 
> > --------------------------------------
> > 北京京垓科技有限公司
> > 王玉贵	wangyugui@e16-tech.com
> > 电话：+86-136-71123776
> > 
> 

--------------------------------------
北京京垓科技有限公司
王玉贵	wangyugui@e16-tech.com
电话：+86-136-71123776