Re: osd pool erasure code stripe width

[Loic Dachary <loic@dachary.org>]

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Hi Tom,

On 20/06/2015 03:18, Deneau, Tom wrote:
> So if I am looking at the performance of a system with
> ceph_erasure_code_benchmark, does this mean I should concentrate
> on the performance with --size 4096 (or whatever stripe width my
> ec pools are going to use)?

Yes. But the erasure code plugin encoding speed is not the only factor. You probably want to try a rados bench instead to get more realistic numbers.

Cheers

> 
> -- Tom
> 
>> -----Original Message-----
>> From: Loic Dachary [mailto:loic@dachary.org]
>> Sent: Friday, June 19, 2015 5:47 PM
>> To: Deneau, Tom; ceph-devel
>> Subject: Re: osd pool erasure code stripe width
>>
>> Hi Tom,
>>
>> A stripe width of 4KB (the default) means the object is encoded 4KB at a
>> time. It does not show in the file written to disk.
>>
>> Cheers
>>
>> On 19/06/2015 22:11, Deneau, Tom wrote:
>>> I am trying to understand the use of "osd pool erasure code stripe width"
>>> For example, I have a single-node system with a k=2,m=1 ec pool and I
>>> write a single 40M object to this pool using rados bench.
>>> But when I look on the disk, I still see only the 3 20M pieces for this
>> object.
>>> Where does the striping get used?
>>>
>>> -- Tom Deneau, AMD
>>>
>>>
>>> Description:
>>> Sets the desired size, in bytes, of an object stripe on every erasure coded
>> pools. Every object if size S will be stored as N stripes and each stripe
>> will be encoded/decoded individually.
>>> Type:
>>> Unsigned 32-bit Integer
>>> Default:
>>> 4096
>>>
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe ceph-devel"
>>> in
>>>
>>
>> --
>> Loïc Dachary, Artisan Logiciel Libre
> 

-- 
Loïc Dachary, Artisan Logiciel Libre


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