Re: [ceph-users] Is Ceph a provider of block device too ?
Sorry, I was mixing concepts. I was thinking of RBD snapshots, which require the file system to be consistent before creating. I have been exploring an idea for creating remote, asynchronous copies of RBD images, hopefully with some form of delayed state updating. I've been reviewing the features of DRBD and LVM to see if these components might add features to make this feasible. The RBD image replication features within a pool do work well and clearly maintain a consistent state for the contained file systems. I use them daily. :) ~jpr On 11/21/2013 12:52 PM, Gregory Farnum wrote: > On Thu, Nov 21, 2013 at 10:13 AM, John-Paul Robinson wrote: >> Is this statement accurate? >> >> As I understand DRBD, you can replicate online block devices reliably, >> but with Ceph the replication for RBD images requires that the file >> system be offline. > It's not clear to me what replication you're asking about with Ceph > here. Ceph is internally replicating the block device to keep it > available in case of server failures, and that's all happening online. > If you want a logically distinct copy (? this seems to be what Dimitri > is referring to with adding a 3rd DRBD copy on another node) then that > model is a lot different than in the classical storage world — it > might be that you're saying "I want 3-copy durability instead of > 2-copy" which you can do online (for all images stored in a given > pool); or you might be after a copy you can use as a stable backup > point, which you can do by taking a snapshot of the image (but here > you probably want to quiesce the filesystem, yes); or you might be > after something completely different which I'm not thinking of... > -Greg > Software Engineer #42 @ http://inktank.com | http://ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
On 11/21/2013 12:52 PM, Gregory Farnum wrote: > If you want a logically distinct copy (? this seems to be what Dimitri > is referring to with adding a 3rd DRBD copy on another node) Disclaimer: I haven't done "stacked drbd", this is from my reading of the fine manual -- I was referring to "stacked" setup where you make a drbd raid-1 w/ 2 hosts and then a drbd raid-1 w/ the that drbd device and another host. I don't believe drbd can keep 3 replicas any other way -- unlike ceph, obviously. -- Dimitri Maziuk Programmer/sysadmin BioMagResBank, UW-Madison -- http://www.bmrb.wisc.edu signature.asc Description: OpenPGP digital signature ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
On Thu, Nov 21, 2013 at 10:13 AM, John-Paul Robinson wrote: > Is this statement accurate? > > As I understand DRBD, you can replicate online block devices reliably, > but with Ceph the replication for RBD images requires that the file > system be offline. It's not clear to me what replication you're asking about with Ceph here. Ceph is internally replicating the block device to keep it available in case of server failures, and that's all happening online. If you want a logically distinct copy (? this seems to be what Dimitri is referring to with adding a 3rd DRBD copy on another node) then that model is a lot different than in the classical storage world — it might be that you're saying "I want 3-copy durability instead of 2-copy" which you can do online (for all images stored in a given pool); or you might be after a copy you can use as a stable backup point, which you can do by taking a snapshot of the image (but here you probably want to quiesce the filesystem, yes); or you might be after something completely different which I'm not thinking of... -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
On 11/21/2013 12:13 PM, John-Paul Robinson wrote: > Is this statement accurate? > > As I understand DRBD, you can replicate online block devices reliably, > but with Ceph the replication for RBD images requires that the file > system be offline. > > Thanks for the clarification, Basic DRBD is RAID-1 over network. You don't "replicate" the filesystem, you have it backed by 2 devices one of which happens to be on another computer. Less basic DRBD allows you to mount your gluster fs on both hosts or add another DRBD on top to mirror your filesystem to a 3rd node. HTH -- Dimitri Maziuk Programmer/sysadmin BioMagResBank, UW-Madison -- http://www.bmrb.wisc.edu signature.asc Description: OpenPGP digital signature ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
Is this statement accurate? As I understand DRBD, you can replicate online block devices reliably, but with Ceph the replication for RBD images requires that the file system be offline. Thanks for the clarification, ~jpr On 11/08/2013 03:46 PM, Gregory Farnum wrote: >> Does Ceph provides the distributed filesystem and block device? > Ceph's RBD is a distributed block device and works very well; you > could use it to replace DRBD. ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
Thank you! I am studying and testing CEPH. I think it will be very good for my needs On 18-11-2013 20:31, Timofey root wrote: On 09 нояб. 2013 г., at 1:46, Gregory Farnum wrote: On Fri, Nov 8, 2013 at 8:49 AM, Listas wrote: Hi ! I have clusters (IMAP service) with 2 members configured with Ubuntu + Drbd + Ext4. Intend to migrate to the use of Ceph and begin to allow distributed access to the data. Does Ceph provides the distributed filesystem and block device? Ceph's RBD is a distributed block device and works very well; you could use it to replace DRBD. The CephFS distributed filesystem is in more of a preview mode and is not supported for general use at this time. Does Ceph work fine in clusters of two members? It should work fine in a cluster of that size, but you're not getting as many advantages over other solutions at such small scales as you do from larger ones. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
On 09 нояб. 2013 г., at 1:46, Gregory Farnum wrote: > On Fri, Nov 8, 2013 at 8:49 AM, Listas wrote: >> Hi ! >> >> I have clusters (IMAP service) with 2 members configured with Ubuntu + Drbd >> + Ext4. Intend to migrate to the use of Ceph and begin to allow distributed >> access to the data. >> >> Does Ceph provides the distributed filesystem and block device? > > Ceph's RBD is a distributed block device and works very well; you > could use it to replace DRBD. The CephFS distributed filesystem is in > more of a preview mode and is not supported for general use at this > time. > >> Does Ceph work fine in clusters of two members? > It should work fine in a cluster of that size, but you're not getting > as many advantages over other solutions at such small scales as you do > from larger ones. > -Greg > Software Engineer #42 @ http://inktank.com | http://ceph.com > ___ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Is Ceph a provider of block device too ?
On Fri, Nov 8, 2013 at 8:49 AM, Listas wrote: > Hi ! > > I have clusters (IMAP service) with 2 members configured with Ubuntu + Drbd > + Ext4. Intend to migrate to the use of Ceph and begin to allow distributed > access to the data. > > Does Ceph provides the distributed filesystem and block device? Ceph's RBD is a distributed block device and works very well; you could use it to replace DRBD. The CephFS distributed filesystem is in more of a preview mode and is not supported for general use at this time. > Does Ceph work fine in clusters of two members? It should work fine in a cluster of that size, but you're not getting as many advantages over other solutions at such small scales as you do from larger ones. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
[ceph-users] Is Ceph a provider of block device too ?
Hi ! I have clusters (IMAP service) with 2 members configured with Ubuntu + Drbd + Ext4. Intend to migrate to the use of Ceph and begin to allow distributed access to the data. Does Ceph provides the distributed filesystem and block device? Does Ceph work fine in clusters of two members? Thanks! -- www.adminlinux.com.br Thiago Henrique ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
