> -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > Brendan Moloney > Sent: 23 March 2015 21:02 > To: Noah Mehl > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: 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 [noahmehl@xxxxxxxxxxxxxxxxxx] > Sent: Monday, March 23, 2015 1:45 PM > To: Brendan Moloney > Cc: ceph-users@xxxxxxxxxxxxxx > Subject: Re: 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 <moloney@xxxxxxxx> > 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 > > _______________________________________________ > > ceph-users mailing list > > ceph-users@xxxxxxxxxxxxxx > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |