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.
--
Craig Ringer