RAID 5/6 Changes Coming For Linux Software RAID (MD)

Written by Michael Larabel in Linux Kernel on 23 April 2015 at 08:39 AM EDT. Add A Comment
Linux 4.1 will feature an updated Multiple Device (MD) driver to improve the RAID 5/6 potential for those relying upon Linux Software RAID.

Neil Brown sent in the md updates for Linux 4.1 this morning and explained, "more updates that usual this time. A few have performance impacts which should mostly be positive, but RAID5 (in particular) can be very work-load sensitive .... we'll have to wait and see."

The RAID 5 and RAID 6 modes can now batch multiple 4K-wide stripe heads to handle a full chunk-wide stripe as a single unit. The RAID 5/6 stripe cache now also grows and shrinks dynamically. RAID 6 specifically can now perform read-modify-write cycles for better performance on larger arrays of six or more devices.

Outside of the RAID 5/6 improvements, there's also experimental support for managing an MD RAID1 across a cluster using the Distributed Lock Manager.

Lastly, resync is now allowed to go faster than the minimum when there's competing I/O.

In total the MD updates for Linux 4.1 brings more than two-thousand lines of new code across more than sixty patches.
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