Thanks for detailed explanation.
Is there any way to disable bucket indexes? We already store index in
our Cassandra cluster and need RADOS only to store objects. We don't
plan to do any listing operations, only PUT and GET.
On 17/03/2013 16:24, Gregory Farnum wrote:
RADOS doesn't store a list of objects. The RADOS Gateway uses a separate data format on top of objects stored in RADOS, and it keeps a per-user list of buckets and a per-bucket index of objects as "omap" objects in the OSDs (which ultimately end up in a leveldb store). A bucket index is currently a single object (stored on one OSD), so that is a performance (and, much later, storage) bottleneck that you can run into with extremely large buckets that see enough traffic. We don't have a precise number (it depends in large part on how powerful your OSDs are) but it's somewhere in the many millions of objects.
-Greg
Software Engineer #42 @ http://inktank.com | http://ceph.com
On Monday, March 11, 2013 at 4:28 PM, Rustam Aliyev wrote:
Thanks Sam,
That's great. I'm trying to understand a bit of RADOS internals and I
went through architecture wiki. Yet unclear about some points.
Where does RADOS store the list of objects (object metadata)? According
to RADOSGW docs S3 bucket listing is available, so it must be stored
somewhere.
Thanks,
Rustam.
On 11/03/2013 20:28, Sam Lang wrote:
On Fri, Mar 8, 2013 at 9:57 PM, Rustam Aliyev <rustam.lists@xxxxxxx (mailto:rustam.lists@xxxxxxx)> wrote:
Hi,
We need to store ~500M of small files (<1MB) and we were looking to RadosGW
solution. We expect about 20 ops/sec (read+write). I'm trying to understand
how Monitoring nodes store Crush maps and what are the limitations.
For instance, is there any recommended max number of objects per Monitoring
node? Does adding more monitoring nodes will help to scale number of small
files and iops (assuming that OSDs not a bottleneck)?
No, the number of objects is unrelated to the monitors, so 3 monitors
should suffice in your case.
-sam
Many thanks,
Rustam.
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