From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dongjun Shin Subject: Re: SSDs and filesystem alignment... Date: Mon, 23 Feb 2009 21:20:16 +0900 Message-ID: <7fe698080902230420m6bbb8635td09e9fc252c320b0@mail.gmail.com> References: <6278d2220902220631r3d89fbcbgc3eef9570c452df3@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Chris Mason , linux-btrfs@vger.kernel.org To: Daniel J Blueman Return-path: In-Reply-To: <6278d2220902220631r3d89fbcbgc3eef9570c452df3@mail.gmail.com> List-ID: On Sun, Feb 22, 2009 at 11:31 PM, Daniel J Blueman wrote: > Does BTRFS perform any journal and/or filesystem structure alignment > (for benefit to SSD longevity and SSD, RAID array and large-sector > device performance) at present? > > ext4's Ted Tso will deliver 128KB alignment with the next release of > e2fsprogs (ie 1.41.4) [1], so perhaps it's a good idea for btrfsprogs > also, if not already available? > > Daniel > > --- > [1] http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase-block-size/ > I think the partition alignment is more important because it has been traditionally hard-coded as 63 sectors. However, the misalignment by filesystem or *fsprogs are of block-sized granularity (usually 4KB). Ted mentioned that the Vista changed the default CHS to 240 heads and 62 sectors. However, AFAIK, what Vista does for that alignment is to change the relative sectors of the MBR [1] -- Dongjun [1] http://www.multibooters.co.uk/partitions.html