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*(unreleased)* |
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New features |
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~~~~~~~~~~~~ |
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- KVM hypervisors can now access RBD storage directly without having to |
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go through a block device. |
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Incompatible/important changes |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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b/doc/install.rst | ||
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$ apt-get install ceph-common |
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KVM userspace access |
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~~~~~~~~~~~~~~~~~~~~ |
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If your cluster uses a sufficiently new version of KVM (you will need at |
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least QEMU 0.14 with RBD support compiled in), you can take advantage of |
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KVM's native support for ceph in order to have better performance and |
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avoid potential deadlocks_ in low memory scenarios. |
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.. _deadlocks: http://tracker.ceph.com/issues/3076 |
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To initialize a cluster with support for this feature, use a command |
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such as:: |
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$ gnt-cluster init \ |
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--enabled-disk-templates rbd \ |
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--ipolicy-disk-templates rbd \ |
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--enabled-hypervisors=kvm \ |
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-D rbd:access=userspace |
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(You may want to enable more templates than just ``rbd``.) |
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You can also change this setting on a live cluster by giving the same |
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switches to ``gnt-cluster modify``, or change those settings at the node |
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group level with ``gnt-group modify``. |
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Configuration file |
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~~~~~~~~~~~~~~~~~~ |
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b/man/gnt-cluster.rst | ||
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When a new RADOS cluster is deployed, the default pool to put rbd |
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volumes (Images in RADOS terminology) is 'rbd'. |
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access |
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If 'userspace', instances will access their disks directly without |
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going through a block device, avoiding expensive context switches |
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with kernel space and the potential for deadlocks_ in low memory |
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scenarios. |
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The default value is 'kernelspace' and it disables this behaviour. |
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This setting may only be changed to 'userspace' if all instance |
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disks in the affected group or cluster can be accessed in userspace. |
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Attempts to use this feature without rbd support compiled in KVM |
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result in a "no such file or directory" error messages. |
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.. _deadlocks: http://tracker.ceph.com/issues/3076 |
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The option ``--maintain-node-health`` allows one to enable/disable |
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automatic maintenance actions on nodes. Currently these include |
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automatic shutdown of instances and deactivation of DRBD devices on |
Also available in: Unified diff