> -----Original Message-----
> From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf Of
> Brendan Moloney
> Sent: 23 March 2015 21:02
> To: Noah Mehl
> Cc: ceph-users@lists.ceph.com
> Subject: Re: [ceph-users] OSD + Flashcache + udev + Partition uuid
>
> This would be in addition to having the journal on SSD. The journal
doesn't
> help at all with small random reads and has a fairly limited ability to
coalesce
> writes.
>
> In my case, the SSDs we are using for journals should have plenty of
> bandwidth/IOPs/space to spare, so I want to see if I can get a little more
out
> of them.
>
> -Brendan
>
> ________________________________________
> From: Noah Mehl [noahm...@combinedpublic.com]
> Sent: Monday, March 23, 2015 1:45 PM
> To: Brendan Moloney
> Cc: ceph-users@lists.ceph.com
> Subject: Re: [ceph-users] OSD + Flashcache + udev + Partition uuid
>
> We deployed with just putting the journal on an SSD directly, why would
this
> not work for you? Just wondering really :)
>
> Thanks!
>
> ~Noah
>
> > On Mar 23, 2015, at 4:36 PM, Brendan Moloney <molo...@ohsu.edu>
> wrote:
> >
> > I have been looking at the options for SSD caching for a bit now. Here
is my
> take on the current options:
> >
> > 1) bcache - Seems to have lots of reliability issues mentioned on
mailing list
> with little sign of improvement.
> >
> > 2) flashcache - Seems to be no longer (or minimally?)
> developed/maintained, instead folks are working on the fork enhanceio.
> >
> > 3) enhanceio - Fork of flashcache. Dropped the ability to skip caching
on
> sequential writes, which many folks have claimed is important for Ceph OSD
> caching performance. (see: https://github.com/stec-
> inc/EnhanceIO/issues/32)
> >
> > 4) LVM cache (dm-cache) - There is now a user friendly way to use dm-
> cache, through LVM. Allows sequential writes to be skipped. You need a
> pretty recent kernel.
> >
> > I am going to be trying out LVM cache on my own cluster in the next few
> weeks. I will share my results here on the mailing list. If anyone else
has
> tried it out I would love to hear about it.
> >
> > -Brendan
> >
> >> In a long term use I also had some issues with flashcache and
enhanceio.
> I've noticed frequent slow requests.
> >>
> >> Andrei
> > _______________________________________________
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> > ceph-users@lists.ceph.com
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
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