You should take a look at this blog post: http://ceph.com/community/ceph-performance-part-2-write-throughput-without-ssd-journals/
The test results shows that using a RAID card with a write-back cache without journal disks can perform better or equivalent to using journal disks with XFS. *As to whether or not it's better to buy expensive controllers and use all of your drive bays for spinning disks or cheap controllers and use some portion of your bays for SSDs/Journals, there are trade-offs. If built right, systems with SSD journals provide higher large block write throughput, while putting journals on the data disks provides higher storage density. Without any tuning both solutions currently provide similar IOP throughput*. Jake On Friday, March 14, 2014, Markus Goldberg <goldb...@uni-hildesheim.de> wrote: > Sorry, > i should have asked a little bit clearer: > Can ceph (or OSDs) be used without journals now ? > The Journal-Parameter seems to be optional ( because of '[...]' ) > > Markus > Am 14.03.2014 12:19, schrieb John Spray: > >> Journals have not gone anywhere, and ceph-deploy still supports >> specifying them with exactly the same syntax as before. >> >> The page you're looking at is the simplified "quick start", the detail >> on osd creation including journals is here: >> http://eu.ceph.com/docs/v0.77/rados/deployment/ceph-deploy-osd/ >> >> Cheers, >> John >> >> On Fri, Mar 14, 2014 at 9:47 AM, Markus Goldberg >> <goldb...@uni-hildesheim.de> wrote: >> >>> Hi, >>> i'm a little bit surprised. I read through the new manuals of 0.77 >>> (http://eu.ceph.com/docs/v0.77/start/quick-ceph-deploy/) >>> In the section of creating the osd the manual says: >>> >>> Then, from your admin node, use ceph-deploy to prepare the OSDs. >>> >>> ceph-deploy osd prepare {ceph-node}:/path/to/directory >>> >>> For example: >>> >>> ceph-deploy osd prepare node2:/var/local/osd0 node3:/var/local/osd1 >>> >>> Finally, activate the OSDs. >>> >>> ceph-deploy osd activate {ceph-node}:/path/to/directory >>> >>> For example: >>> >>> ceph-deploy osd activate node2:/var/local/osd0 node3:/var/local/osd1 >>> >>> >>> In former versions the osd was created like: >>> >>> ceph-deploy -v --overwrite-conf osd --fs-type btrfs prepare >>> bd-0:/dev/sdb:/dev/sda5 >>> >>> ^^^^^^^^^^ Journal >>> As i remember defining and creating a journal for each osd was a must. >>> >>> So the question is: Are Journals obsolet now ? >>> >>> -- >>> MfG, >>> Markus Goldberg >>> >>> ------------------------------------------------------------ >>> -------------- >>> Markus Goldberg Universität Hildesheim >>> Rechenzentrum >>> Tel +49 5121 88392822 Marienburger Platz 22, D-31141 Hildesheim, Germany >>> Fax +49 5121 88392823 email goldb...@uni-hildesheim.de >>> ------------------------------------------------------------ >>> -------------- >>> >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >>> > > -- > MfG, > Markus Goldberg > > -------------------------------------------------------------------------- > Markus Goldberg Universität Hildesheim > Rechenzentrum > Tel +49 5121 88392822 Marienburger Platz 22, D-31141 Hildesheim, Germany > Fax +49 5121 88392823 email goldb...@uni-hildesheim.de > -------------------------------------------------------------------------- > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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