Hi Jan,
Out of curiosity did you ever try dm-cache? I've been meaning to give
it a spin but haven't had the spare cycles.
Mark
On 08/18/2015 04:00 AM, Jan Schermer wrote:
I already evaluated EnhanceIO in combination with CentOS 6 (and backported 3.10 and 4.0 kernel-lt if I remember correctly).
It worked fine during benchmarks and stress tests, but once we run DB2 on it it panicked within minutes and took all the data with it (almost literally - files that werent touched, like OS binaries were b0rked and the filesystem was unsalvageable).
If you disregard this warning - the performance gains weren't that great either, at least in a VM. It had problems when flushing to disk after reaching dirty watermark and the block size has some not-well-documented implications (not sure now, but I think it only cached IO _larger_than the block size, so if your database keeps incrementing an XX-byte counter it will go straight to disk).
Flashcache doesn't respect barriers (or does it now?) - if that's ok for you than go for it, it should be stable and I used it in the past in production without problems.
bcache seemed to work fine, but I needed to
a) use it for root
b) disable and enable it on the fly (doh)
c) make it non-persisent (flush it) before reboot - not sure if that was possible either.
d) all that in a customer's VM, and that customer didn't have a strong technical background to be able to fiddle with it...
So I haven't tested it heavily.
Bcache should be the obvious choice if you are in control of the environment. At least you can cry on LKML's shoulder when you lose data :-)
Jan
On 18 Aug 2015, at 01:49, Alex Gorbachev <ag@xxxxxxxxxxxxxxxxxxx> wrote:
What about https://github.com/Frontier314/EnhanceIO? Last commit 2
months ago, but no external contributors :(
The nice thing about EnhanceIO is there is no need to change device
name, unlike bcache, flashcache etc.
Best regards,
Alex
On Thu, Jul 23, 2015 at 11:02 AM, Daniel Gryniewicz <dang@xxxxxxxxxx> wrote:
I did some (non-ceph) work on these, and concluded that bcache was the best
supported, most stable, and fastest. This was ~1 year ago, to take it with
a grain of salt, but that's what I would recommend.
Daniel
________________________________
From: "Dominik Zalewski" <dzalewski@xxxxxxxxxxx>
To: "German Anders" <ganders@xxxxxxxxxxxx>
Cc: "ceph-users" <ceph-users@xxxxxxxxxxxxxx>
Sent: Wednesday, July 1, 2015 5:28:10 PM
Subject: Re: any recommendation of using EnhanceIO?
Hi,
I’ve asked same question last weeks or so (just search the mailing list
archives for EnhanceIO :) and got some interesting answers.
Looks like the project is pretty much dead since it was bought out by HGST.
Even their website has some broken links in regards to EnhanceIO
I’m keen to try flashcache or bcache (its been in the mainline kernel for
some time)
Dominik
On 1 Jul 2015, at 21:13, German Anders <ganders@xxxxxxxxxxxx> wrote:
Hi cephers,
Is anyone out there that implement enhanceIO in a production environment?
any recommendation? any perf output to share with the diff between using it
and not?
Thanks in advance,
German
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