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Add docs on OCF bdev describing its usage

Change-Id: Icafadf7a406870265f1404bb80d0af4a0bea219a
Signed-off-by: Vitaliy Mysak <vitaliy.mysak@intel.com>
Reviewed-on: https://review.gerrithub.io/c/437689
Reviewed-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
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Vitaliy Mysak 2018-12-18 23:34:28 +00:00 committed by Darek Stojaczyk
parent 3bd76a3b3a
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doc/bdev.md
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@ -235,6 +235,35 @@ To delete an aio bdev use the delete_aio_bdev command.
`rpc.py delete_aio_bdev aio0` `rpc.py delete_aio_bdev aio0`
# OCF Virtual bdev {#bdev_config_cas}
OCF virtual bdev module is based on [Open CAS Framework](https://github.com/Open-CAS/) - a
high performance block storage caching meta-library.
To enable the module, configure SPDK with `--with-ocf=/path/to/ocf/library`.
OCF bdev can be used to enable caching for any underlying bdev.
Below is an example command for creating OCF bdev:
`rpc.py construct_ocf_bdev Cache1 wt Malloc0 Nvme0n1`
This command will create new OCF bdev `Cache1` having bdev `Malloc0` as caching-device
and `Nvme0n1` as core-device and initial cache mode `Write-Through`.
`Malloc0` will be used as cache for `Nvme0n1`, so data written to `Cache1` will be present
on `Nvme0n1` eventually.
By default, OCF will be configured with cache line size equal 4KiB
and non-volatile metadata will be disabled.
To remove `Cache1`:
`rpc.py delete_ocf_bdev Cache1`
During removal OCF-cache will be stopped and all cached data will be written to the core device.
Note that OCF has a per-device RAM requirement
of about 56000 + _cache device size_ * 58 / _cache line size_ (in bytes).
To get more information on OCF
please visit [OCF documentation](https://open-cas.github.io/doxygen/ocf/).
# Malloc bdev {#bdev_config_malloc} # Malloc bdev {#bdev_config_malloc}
Malloc bdevs are ramdisks. Because of its nature they are volatile. They are created from hugepage memory given to SPDK Malloc bdevs are ramdisks. Because of its nature they are volatile. They are created from hugepage memory given to SPDK