Comments on: HAMMER version 7

By: Anonymous

Anonymous — Sat, 15 Apr 2017 07:17:32 +0000

Modern CPUs have a hardware crc32 instruction.
Matt probably didn’t want to use it to preserve compatibility with previous machines.

By: Justin Sherrill

Justin Sherrill — Sat, 15 Apr 2017 01:07:56 +0000

You can change code that is not executed.

By: Timothy

Timothy — Fri, 14 Apr 2017 21:23:00 +0000

I’m confused by the commit message.

It says:

“Add support for version 7 which changes the CRC mechanic from the old slow CRC code to the faster ISCSI CRC code. ***We don’t use the CRC instruction yet***”

(Emphasis is mine.)

So the commit message says they are changing the slow CRC code to faster ISCSI CRC code … but then they say they don’t use CRC yet?

How can you change something that isn’t used yet?

By: Anonymous

Anonymous — Fri, 14 Apr 2017 06:19:36 +0000

Adam…

Because most of us are still using H1 and it is a stable, robust filesystem that still continues to see nice improvements. I for one am very appreciative of the new CRC code. It makes SSD-based systems (or large RAID arrays) that much more performant.

By: Adam Weitner

Adam Weitner — Fri, 14 Apr 2017 03:40:36 +0000

Why is development still being done on hammer1 (with the expedition of big fixes and security issue)?

Should all file system efforts be spent on hammer2?