Re: why the erasure code pool not support random write?

[Gregory Farnum <greg@xxxxxxxxxxx>]

This is a common constraint in many erasure coding storage system. It arises because random writes turn into a read-modify-write cycle (in order to redo the parity calculations). So we simply disallow them in EC pools, which works fine for the target use cases right now.

-Greg

On Monday, October 20, 2014, 池信泽 <xmdxcxz@xxxxxxxxx> wrote:

hi, cephers:

      When I look into the ceph source code, I found the erasure code pool not support 

the random write, it only support the append write. Why? Is that random write of is erasure code high cost and the performance of the deep scrub is very poor?

 Thanks.

-- 
Software Engineer #42 @ http://inktank.com | http://ceph.com
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