Commit 9d893251 authored by Vitaliy Mysak's avatar Vitaliy Mysak Committed by Darek Stojaczyk
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OCF: add user docs 



Add docs on OCF bdev describing its usage

Change-Id: Icafadf7a406870265f1404bb80d0af4a0bea219a
Signed-off-by: default avatarVitaliy Mysak <vitaliy.mysak@intel.com>
Reviewed-on: https://review.gerrithub.io/c/437689


Reviewed-by: default avatarDarek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Reviewed-by: default avatarChangpeng Liu <changpeng.liu@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
parent 3bd76a3b

doc/bdev.md

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Original line number Diff line number Diff line
@@ -235,6 +235,35 @@ To delete an aio bdev use the delete_aio_bdev command. 


`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 bdevs are ramdisks. Because of its nature they are volatile. They are created from hugepage memory given to SPDK