On 14. sep. 2017 00:34, James Okken wrote:
Thanks Ronny! Exactly the info I need. And kinda of what I thought the answer would be as I was typing and thinking clearer about what I was asking. I just was hoping CEPH would work like this since the openstack fuel tools deploy CEPH storage nodes easily. I agree I would not be using CEPH for its strengths. I am interested further in what you've said in this paragraph though: "if you want to have FC SAN attached storage on servers, shareable between servers in a usable fashion I would rather mount the same SAN lun on multiple servers and use a cluster filesystem like ocfs or gfs that is made for this kind of solution." Please allow me to ask you a few questions regarding that even though it isn't CEPH specific. Do you mean gfs/gfs2 global file system? Does ocfs and/or gfs require some sort of management/clustering server to maintain and manage? (akin to a CEPH OSD) I'd love to find a distributed/cluster filesystem where I can just partition and format. And then be able to mount and use that same SAN datastore from multiple servers without a management server. If ocfs or gfs do need a server of this sort does it needed to be involved in the I/O? or will I be able to mount the datastore, similar to any other disk and the IO goes across the fiberchannel?
i only have experience with ocfs. but i think gfs works similarish. There are quite a few cluster filesystems to choose from. https://en.wikipedia.org/wiki/Clustered_file_system
servers that are mounting ocfs shared filesystems must have ocfs2-tools installed. have access to the common shared FC lun via FC. they need to be aware of the other ocfs servers of the same lun, that you define in a /etc/ocfs/cluster.conf configfile and the ocfs daemon must be running.
then it is just a matter of making the ocfs (on one server) and adding it to fstab (of all servers) and mount.
One final question, if you don't mind, do you think I could use ext4or xfs and "mount the same SAN lun on multiple servers" if I can guarantee each server will only right to its own specific directory and never anywhere the other servers will be writing? (I even have the SAN mapped to each server using different lun's)
mounting the same (non cluster) filesystem on multiple servers is guaranteed to destroy the filesystem, you will have multiple servers writing in the same metadata area, the same journal area and generaly shitting over each other. luckily i think most modern filesystems would detect that the FS is mounted somewhere else and prevent you from mounting it again without big fat warnings.
kind regards Ronny Aasen _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
