We see newly added OSD take long time to become active, it is
fetching old osdmaps from monitors. Curious why it need that much
historical ? The cluster is stable , no osd down/out except the ongoing
cap add (one osd at a time).
root@host:~# ceph osd getmap | head -5
got osdmap epoch 324825
In *mapper.c* file of Ceph CRUSH, I am trying to understand the definition
of a linux macro ```*S64_MIN*``` used in the following ```*else*```
condition i.e. ```*draw = S64_MIN*```.
Which exact decimal value is meant here for ```*S64_MIN*```?
u = hash(bucket->h.hash, x, ids[i], r);
u &= 0xffff;
ln = crush_ln(u) - 0x1000000000000ll;
__s64 draw = div64_s64(ln, weights[i]);
__s64 draw = S64_MIN;
// #define S64_MAX ((s64)(U64_MAX >> 1))
// #define S64_MIN ((s64)(-S64_MAX -1))
if (i == 0 || draw > high_draw)
high = i;
high_draw = draw;
There's a framework  I've been working on for a while to deploy
Ceph in the cloud. For now, this is done through the Linode, LLC cloud
Primarily I use this for testing CephFS performance/behavior. For
example, it's fairly simple to create a decent sized test cluster with
150GB MDSs and 16x 16GB OSDs for a humble 1.7TB usable storage. Then
provision 100+ client machine nodes for executing workflows against
the Ceph cluster. This has been very useful for isolating aberrant
behaviors that are only uncovered at scale. All of the code/playbooks
I use for this purpose are also in the ceph-linode repository.
Early versions of this project used ceph-ansible but I have updated
the code to use the new cephadm deployment technology  in Ceph
Octopus release. The ansible playbook to deploy the cluster  is
Anyway, I thought it may be useful to the broader community to have an
option to try out cephadm on a throwaway cluster for pennies per hour
through a VPS provider. Getting a small cluster started should take
less than 10 minutes by following the README. I hope some folks out
there find this useful for their own testing. Feedback is welcome.
Full disclosure: I have no relationship with Linode except as a customer.
Patrick Donnelly, Ph.D.
He / Him / His
Principal Software Engineer
Red Hat Sunnyvale, CA
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