On Wed, Aug 12, 2015 at 7:21 PM, Yan, Zheng <ukernel@xxxxxxxxx> wrote:
On Thu, Aug 13, 2015 at 7:05 AM, Bob Ababurko <bob@xxxxxxxxxxxx> wrote:
>
> If I am using a more recent client(kernel OR ceph-fuse), should I still be
> worried about the MDS's crashing? I have added RAM to my MDS hosts and its
> my understanding this will also help mitigate any issues, in addition to
> setting mds_bal_frag = true. Not having used cephfs before, do I always
> need to worry about my MDS servers crashing all the time, thus the need for
> setting mds_reconnect_timeout to 0? This is not ideal for us nor is the
> idea of clients not able to access their mounts after a MDS recovery.
>
It's unlikely this issue will happen again. But I can't guarantee no
other issue.
no need to set mds_reconnect_timeout to 0.
ok, Good to know.
> I am actually looking for the most stable way to implement cephfs at this
> point. My cephfs cluster contains millions of small files, so many inodes
> if that needs to be taken into account. Perhaps I should only be using one
> MDS node for stability at this point? Is this the best way forward to get a
> handle on stability? I'm also curious if I should I set my mds cache size
> to a number greater than files I have in the cephfs cluster? If you can
> give some key points to configure cephfs to get the best stability and if
> possible, availability.....this would be helpful to me.
One active MDS is the most stable setup. Adding a few standby MDS
should not hurt stability.
You can't set mds cache size to a number greater than files in the
fs, it requires lots of memory.
I'm not sure what amount of RAM you consider to be 'lots' but I would really like to understand a bit more about this. Perhaps a rule of thumb? It there an advantage to more RAM & large mds cache size? We plan on putting close to a billion small files in this pool via cephfs so what should we be considering when sizing our MDS hosts OR change to the MDS config? Basically, what should we OR should not be doing when we have a cluster with this many files? Thanks!
Yan, Zheng
>
> thanks again for the help.
>
> thanks,
> Bob
>
_______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
