On 05/29/2013 01:24 AM, Wido den Hollander wrote:
On 05/29/2013 10:14 AM, Wido den Hollander wrote:
Hi,
Is there a way to find out if a cluster is near full via librados?
Yes, there is. (Thanks tnt on IRC!)
There is ofcourse rados_cluster_stat which will give you:
struct rados_cluster_stat_t {
uint64_t kb, kb_used, kb_avail;
uint64_t num_objects;
};
One thing here is however that you don't know to what the (near)full
ratio has been set to. So you have to do your own guessing.
Aside: Soon there will be a librados interface for issuing commands like
ceph pg dump and getting the response (in JSON if desired), if that's
going to be helpful.
The reason I'm asking is that I'm working on a deployment of the RADOS
Gateway and one of the potential problems I see is that the RADOS
Gateway can keep writing and filling up the whole cluster.
So, with the cluster stat information we could implement:
rgw_refuse_write_above_ratio DOUBLE 0.90
It's obvious that it's the admin's responsibility to make sure that
doesn't happen, but what I'd like to do is make the RADOS Gateway deny
PUT requests when the cluster is near full.
That way normal meta data operations (thus writes) can continue, but new
objects won't be accepted until the cluster has enough space available.
This might also be useful for librbd. Refuse the creation of new RBD
images so that existing images can continue operating.
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