Oops - Nonetheless in on my environments -> Nonetheless in *one of* my environments
On 2 February 2015 at 16:12, Colin Taylor <colin.tay...@gmail.com> wrote: > Thanks all for you input. > > I'm aware of the overlap, I'm aware I need to turn Ceph replication off, > I'm aware this isn't ideal. Nonetheless in on my environments instead of > raw disk to install C* on, I'm likely to just have Ceph storage. This is a > fully managed environment (excepting for C*) and that's their standard. > > cheers > Colin > > On 2 February 2015 at 14:42, Daniel Compton < > daniel.compton.li...@gmail.com> wrote: > >> As Jan has already mentioned, Ceph and Cassandra do almost all of the >> same things. "Replicated self healing data storage on commodity hardware >> without a SPOF" describes both of these systems. If you did manage to get >> it running it would be a nightmare to reason about what's happening at the >> disk and network level. >> >> You're going to get write amplification by your replication factor of >> both Cassandra, and Ceph unless you turn one of them down. This impacts >> disk I/O, disk space, CPU, and network bandwidth. If you turned down Ceph >> replication I think it would be possible for all of the replicated data for >> some chunk to be stored on one node and be at risk of loss. E.g. 1x Ceph, >> 3x Cassandra replication could store all 3 Cassandra replicas on the same >> Ceph node. 3x Ceph, 1x Cassandra would be safer, but presumably slower. >> >> Lastly Cassandra is designed around running against local disks, you will >> lose a lot of the advantages of this running it on Ceph. >> >> Daniel. >> >> On Mon, 2 Feb 2015 at 1:11 am Baskar Duraikannu < >> baskar.duraika...@outlook.com> wrote: >> >>> What is the reason for running Cassandra on Ceph? I have both running >>> in my environment but doing different things - Cassandra as transactional >>> store and Ceph as block storage for storing files. >>> ------------------------------ >>> From: Jan <cne...@yahoo.com> >>> Sent: 2/1/2015 2:53 AM >>> To: user@cassandra.apache.org >>> Subject: Re: Cassandra on Ceph >>> >>> Colin; >>> >>> Ceph is a block based storage architecture based on RADOS. >>> It comes with its own replication & rebalancing along with a map of the >>> storage layer. >>> >>> Some more details & similarities: >>> a)Ceph stores a client’s data as objects within storage pools. (think >>> of C* partitions) >>> b) Using the CRUSH algorithm, Ceph calculates which placement group >>> should contain the object, (C* primary keys & vnode data distribution) >>> c) and further calculates which Ceph OSD Daemon should store the >>> placement group (C* node locality) >>> d) The CRUSH algorithm enables the Ceph Storage Cluster to scale, >>> rebalance, and recover dynamically (C* big table storage architecture). >>> >>> Summary: >>> C* comes with everything that Ceph provides (with the exception of >>> block storage). >>> There is no value add that Ceph brings to the table that C* does not >>> already provide. >>> I seriously doubt if C* could even work out of the box with yet another >>> level of replication & rebalancing. >>> >>> Hope this helps >>> Jan/ >>> >>> C* Architect >>> >>> >>> >>> >>> >>> >>> On Saturday, January 31, 2015 7:28 PM, Colin Taylor < >>> colin.tay...@gmail.com> wrote: >>> >>> >>> I may be forced to run Cassandra on top of Ceph. Does anyone have >>> experience / tips with this. Or alternatively, strong reasons why this >>> won't work. >>> >>> cheers >>> Colin >>> >>> >>> >
