From mboxrd@z Thu Jan 1 00:00:00 1970 From: mail ignored <0.bugs.only.0@gmail.com> Subject: when/why to use diffferent raid values for btrfs data & metadata? Date: Sat, 23 Jan 2010 20:02:33 -0800 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 To: linux-btrfs@vger.kernel.org Return-path: List-ID: Hi, Just getting started with btrfs. I understand that btrfs stores data/metadata in two different tree structures =96 one for file/directory names, and one for data blocks. Reading @, http://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devic= es Use raid10 for both data and metadata mkfs.btrfs -m raid10 -d raid10 /dev/sdb /dev/sdc /dev/sdd /dev/sde and @, "Churning Butter(FS): An Interview with Chris Mason" http://www.linux-mag.com/id/7329 CM Today you can do this: mkfs.btrfs -m raid1 -d raid10 /dev/sda /dev/sdb /dev/sdc /dev/sdd And you=92ll get metadata on raid1 and data on raid10. The raid10 will use all four drives and the raid1 will use two drives at a time. Yes, btrfs allows you to pick different values for data or metadata. The fact that I *can* setup data & metadata differently is clear. But I'm not at all clear *why* I'd want to, or what the advantages are. I'd guess it's a balance/combination of performance & resiliency. Naively "-m raid10 -d raid10" seems to make the most sense -- if i have it, use it. Are there any benchmarks, guidelines or recommendations? -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html