XFS write speeds: software RAID 0/5/6 across 45 spindles

Wed, 02 Jan 2013 16:05:07 +0000

We’re currently building a new storage server to store low-priority data (tertiary backups, etc). One of the requirements for the project is that it needs to be on cheap storage (as opposed to expensive enterprise SAN/NAS). After some research we decided to build a Backblaze pod. Backblaze used 3TB Hitachi drives in their system, but the ones they listed in their blog post are discontinued and the reviews for all other 3TB+ drives were terrible, so we went with Samsung ST2000DL004 2TB 7200 RPM drives. Like Backblaze, we’re going with software raid, but I figured a good first step would be to figure out what RAID level we want to use, and if we want to use the mdadm/LVM mish-mosh Backblaze uses, or find something simpler. For my testing I created a RAID6 of all 45 drives and created a single XFS volume (XFS’s size limit is ~8 exabytes vs ext4’s 16TB). Ext4 may present some performance advantages, but the management overhead is probably not worth it in our case.

Raid5 on Evan Hoffman

XFS write speeds: software RAID 0/5/6 across 45 spindles