Ceph

h1. Rbd - Copy-on-read for clones in kernel rbd client

h3. Summary

Add feature copy-on-read in kernel rbd client to improve read performance of clones

h3. Owners

* Min Chen (minchen@ubuntukylin.com)

* Li Wang (liwang@ubuntukylin.com)

* Name

h3. Interested Parties

* Name (Affiliation)

* Name (Affiliation)

* Name

h3. Current Status

The kernel rbd client does not support clones copy-on-read. We have implement it in librbd 

at File:/C:\Users\ADMINI~1\AppData\Local\Temp\[5UQ[BL(6~BS2JV6W}N6[%S.pnghttps://github.com/ceph/ceph/pull/1808

h3. Detailed Description

Network latency will be the bottleneck of reading object not exist in clone , because it will read object 

from parent. We will use the same algorithm of copy-on-read in librbd. Firstly, read data from clone if 

it exists, or else send request to its parent. Secondly, after get the object from parent, in callback function

write it directly into clone asynchronously with cls copyup. In addition, read the entire object from parent.

h3. Work items

h4. Coding tasks

# Add an copy-on-read option

# In function rbd_img_obj_request_submit(), sending read request to parent.

h4. Build / release tasks

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h4. Documentation tasks

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h4. Deprecation tasks

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