Re: [dm-devel] dm-thin: Why is DATA_DEV_BLOCK_SIZE_MIN_SECTORS set to 64k?

2018-06-12 Thread Joe Thornber
On Sat, Jun 09, 2018 at 07:31:54PM +, Eric Wheeler wrote: > I understand the choice. What I am asking is this: would it be safe to > let others make their own choice about block size provided they are warned > about the metadata-chunk-size/pool-size limit tradeoff? > > If it is safe, can

Re: [dm-devel] dm-thin: Why is DATA_DEV_BLOCK_SIZE_MIN_SECTORS set to 64k?

2018-06-09 Thread Zdenek Kabelac
Dne 9.6.2018 v 21:31 Eric Wheeler napsal(a): On Fri, 18 May 2018, Zdenek Kabelac wrote: Dne 18.5.2018 v 01:36 Eric Wheeler napsal(a): Hello all, Is there a technical reason that DATA_DEV_BLOCK_SIZE_MIN_SECTORS is limited to 64k? I realize that the metadata limits the maximum mappable pool

Re: [dm-devel] dm-thin: Why is DATA_DEV_BLOCK_SIZE_MIN_SECTORS set to 64k?

2018-06-09 Thread Eric Wheeler
On Fri, 18 May 2018, Zdenek Kabelac wrote: > Dne 18.5.2018 v 01:36 Eric Wheeler napsal(a): > > Hello all, > > > > Is there a technical reason that DATA_DEV_BLOCK_SIZE_MIN_SECTORS is > > limited to 64k? > > > > I realize that the metadata limits the maximum mappable pool size, so it > > needs to

Re: [dm-devel] dm-thin: Why is DATA_DEV_BLOCK_SIZE_MIN_SECTORS set to 64k?

2018-05-18 Thread Zdenek Kabelac
Dne 18.5.2018 v 01:36 Eric Wheeler napsal(a): Hello all, Is there a technical reason that DATA_DEV_BLOCK_SIZE_MIN_SECTORS is limited to 64k? I realize that the metadata limits the maximum mappable pool size, so it needs to be bigger for big pools---but it is also the minimum COW size. Looking

[dm-devel] dm-thin: Why is DATA_DEV_BLOCK_SIZE_MIN_SECTORS set to 64k?

2018-05-17 Thread Eric Wheeler
Hello all, Is there a technical reason that DATA_DEV_BLOCK_SIZE_MIN_SECTORS is limited to 64k? I realize that the metadata limits the maximum mappable pool size, so it needs to be bigger for big pools---but it is also the minimum COW size. Looking at the code this is enforced in