Thread: postgres block size alignment with filesystem block size
Hello, I am setting up a new postgres production server in a managed hosting environment. I dont have much insight into the underlying disk architecture but the filesystem I have been presented with has a 4k block size. Postgres defaults to 8k block size; would it be beneficial to repave the filesystem at an 8k block size or problematic to leave it at 4k? I have seen posts suggesting alignment of the postgres block size and the file system block size and the raid block size, but wonder if a multiple is sufficient or if it should match exactly.
Thank you
Mike
Mike Broers <mbroers@gmail.com> writes: > Hello, I am setting up a new postgres production server in a managed > hosting environment. I dont have much insight into the underlying disk > architecture but the filesystem I have been presented with has a 4k block > size. Postgres defaults to 8k block size; would it be beneficial to repave > the filesystem at an 8k block size or problematic to leave it at 4k? I doubt it's worth the trouble to change it. Most filesystems default to 4k or smaller block sizes, so that's what PG is accustomed to run on. I think it would only really be an issue if PG's block size weren't a multiple of the filesystem block. regards, tom lane
On Wed, Jun 06, 2012 at 12:24:35PM -0400, Tom Lane wrote: > Mike Broers <mbroers@gmail.com> writes: > > Hello, I am setting up a new postgres production server in a managed > > hosting environment. I dont have much insight into the underlying disk > > architecture but the filesystem I have been presented with has a 4k block > > size. Postgres defaults to 8k block size; would it be beneficial to repave > > the filesystem at an 8k block size or problematic to leave it at 4k? > > I doubt it's worth the trouble to change it. Most filesystems default > to 4k or smaller block sizes, so that's what PG is accustomed to run on. > I think it would only really be an issue if PG's block size weren't a > multiple of the filesystem block. I have heard about performance issues when the virtual machine block size isn't aligned with the host OS block size. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +