Re: Block_Size on NTFS

Craig Ringer wrote:
> Bruce Momjian wrote:
> > postgresqlgeneral.domain.thewild_codata@spamgourmet.com wrote:
> >> Hi all !
> >>
> >> Reading through the list of settings returned by "SHOW ALL", I noticed
> >> the "block_size" variable, which defaults to 8192.
> >>
> >> Running on Windows Server, my data directory is on an NTFS partition.
> >> Running CHKDSK on this partition tells me that there are "4096 bytes in
> >> each allocation unit."
> >>
> >> Are these allocation units the same as the "block_size", or does this
> >> only have to do with disk geometry ?
> >> If they are the same, is it important that they match ?
> >
> > It is not necessary they match.  It just means that Postgres extends
> > files in 8k chunks while your file system extends them in 4k chunks.
>
> ... though it's a really good idea that the Pg block size be a multiple
> of the file system block size. Since most file systems use blocks of 4k
> or some other 2^x power less than that, Pg's 8k block size is basically
> always going to be fine.
>
> New hard disks are moving to 4k physical blocks, so you won't have any
> issues on new 4k block disks either.

Yes, it would be suboptimial if our block size was smaller than the file
system block size.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +