From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Chmielewski Subject: Re: [PATCH] Btrfs-progs: btrfs file system size should be bigger then 256m Date: Mon, 05 Jan 2009 16:49:16 +0100 Message-ID: <49622BFC.7040105@wpkg.org> References: <49621CBA.2080802@wpkg.org> <49622525.80001@schleiser.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed To: Kaspar Schleiser , linux-btrfs@vger.kernel.org Return-path: In-Reply-To: <49622525.80001@schleiser.de> List-ID: Kaspar Schleiser schrieb: > Hey, > > Tomasz Chmielewski wrote: >>> This has been bothering me for some time. Why does btrfs need to have >>> a disk greater then 256M? I could see a much smaller limit, say 16M >>> but why so much? The file system itself does not need that much space >>> for its own use. >> >> In other words, 256M limit rather disqualifies btrfs as a filesystem >> i.e. for /boot, doesn't it? > When 1G is just 10c? Maybe when talking about traditional HDDs. Anything flash-based is still $2-$5 per 1G. I have some SAN devices booting off 512MB or 1G builtin flash. Having 256M for /boot there would not leave much more space for the operating system. Why separate /boot? It's still needed for encrypted rootfs or more fancy partitioning (like / on LVM, at least until GRUB2 is stable and is shipped by major distros). Seriously, what are the technical reasons that btrfs needs so much space for a minimal filesystem? Just 2 MB is enough for mkfs.ext4 to create a valid filesystem. Also, the patch seems to be incomplete - i.e. what will happen if we try to btrfs-convert a 50MB ext3 filesystem into btrfs? -- Tomasz Chmielewski http://wpkg.org