Mailinglist Archive: opensuse (1470 mails)

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Re: [opensuse] Re: any real-life experiences with bache / dm-cache and ssd ?
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Fri, 12 Feb 2016 21:16:55 +0100
  • Message-id: <n9lejo$tk0$1@saturn.local.net>
Malcolm wrote:

On Thu 11 Feb 2016 03:35:16 PM CST, Per Jessen wrote:

Per Jessen wrote:

Malcolm wrote:

On Thu 11 Feb 2016 08:23:17 AM CST, Per Jessen wrote:

I was studying bcache yesterday and just wondered if anyone had any
real-life experiences to share?


Hi
I wrote a blog entry about it
https://forums.opensuse.org/entry.php/159-Setting-up-bcache-on-openSUSE-13-2


I had to log in to get access, is that intentional?

On random read, it slows down quite a bit, I guess that is because it's
actually reading from disk?
I'm surprised to see how slow "Mixed 70/30 random read and write with
8K block size" is. Random read is reading from disk, but why is the
random write so slow?



Hi
Possibly because it's set at writethough?

Ah, okay.

Test and tweak, things have also improved with later kernels, I've
found it robust with bcache/xfs on RAID mirrors.

Maybe a read here for tweaks;
https://www.kernel.org/doc/Documentation/bcache.txt

Thanks - I think I might acquire one of those 128Gb SSDs on PCIe, they're
not too expensive to experiment with.


/Per

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