ceph/doc/rbd/iscsi-monitoring.rst

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Monitoring the iSCSI gateways
-----------------------------
Ceph provides an additional tool for iSCSI gateway environments
to monitor performance of exported RADOS Block Device (RBD) images.
The ``gwtop`` tool is a ``top``-like tool that displays aggregated
performance metrics of RBD images that are exported to clients over
iSCSI. The metrics are sourced from a Performance Metrics Domain Agent
(PMDA). Information from the Linux-IO target (LIO) PMDA is used to list
each exported RBD image with the connected client and its associated I/O
metrics.
**Requirements:**
- A running Ceph iSCSI gateway
**Installing:**
#. As ``root``, install the ``ceph-iscsi-tools`` package on each iSCSI
gateway node:
::
# yum install ceph-iscsi-tools
#. As ``root``, install the performance co-pilot package on each iSCSI
gateway node:
::
# yum install pcp
#. As ``root``, install the LIO PMDA package on each iSCSI gateway node:
::
# yum install pcp-pmda-lio
#. As ``root``, enable and start the performance co-pilot service on
each iSCSI gateway node:
::
# systemctl enable pmcd
# systemctl start pmcd
#. As ``root``, register the ``pcp-pmda-lio`` agent:
::
cd /var/lib/pcp/pmdas/lio
./Install
By default, ``gwtop`` assumes the iSCSI gateway configuration object is
stored in a RADOS object called ``gateway.conf`` in the ``rbd`` pool.
This configuration defines the iSCSI gateways to contact for gathering
the performance statistics. This can be overridden by using either the
``-g`` or ``-c`` flags. See ``gwtop --help`` for more details.
The LIO configuration determines which type of performance statistics to
extract from performance co-pilot. When ``gwtop`` starts it looks at the
LIO configuration, and if it find user-space disks, then ``gwtop``
selects the LIO collector automatically.
**Example ``gwtop`` Outputs**
::
gwtop 2/2 Gateways CPU% MIN: 4 MAX: 5 Network Total In: 2M Out: 3M 10:20:00
Capacity: 8G Disks: 8 IOPS: 503 Clients: 1 Ceph: HEALTH_OK OSDs: 3
Pool.Image Src Size iops rMB/s wMB/s Client
iscsi.t1703 500M 0 0.00 0.00
iscsi.testme1 500M 0 0.00 0.00
iscsi.testme2 500M 0 0.00 0.00
iscsi.testme3 500M 0 0.00 0.00
iscsi.testme5 500M 0 0.00 0.00
rbd.myhost_1 T 4G 504 1.95 0.00 rh460p(CON)
rbd.test_2 1G 0 0.00 0.00
rbd.testme 500M 0 0.00 0.00
In the *Client* column, ``(CON)`` means the iSCSI initiator (client) is
currently logged into the iSCSI gateway. If ``-multi-`` is displayed,
then multiple clients are mapped to the single RBD image.