MD In Linux 4.10 Adds RAID5 Writeback Cache Feature, FAILFAST
Written by Michael Larabel in Linux Kernel on 14 December 2016 at 02:29 PM EST. 2 Comments
LINUX KERNEL --
The Linux MD/RAID code was updated today in Git for the Linux 4.10 kernel with new functionality.

One of the new MD additions for Linux 4.10 is a RAID5 write-back cache feature. This aggregates writes to make a full stripe write and reduce read-modify-writes. MD maintainer Shaohua Li reported this feature should be good for workloads doing sequential writes followed by fsync. For now though this RAID5 cache feature is considered experimental and disabled by default. The r5c_journal_mode sysfs entry is used for setting the write-back or write-through cache mode.

"Failfast" support has been added. The failfast flag fails I/O to broken RAID disks to improve the latency. More details on the FAILFAST work via this earlier patch series.

Also new to the MD code for Linux 4.10 is AVX2 instructions are supported now along the RAID6 parity calculation path. Advanced Vector Extensions 2 are supported with Intel Haswell and newer or AMD Carrizo/Zen.

Various other MD changes -- including bug-fixes -- can also be found in this pull. Check it out for more details.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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