So, I want a speed like this, not a linear reducation when replication
size increase:
rep_size 1 2 3
4 5 ...
n
write： 78.8 MB/s 39.38 MB/s (38.7 MB/s) (37.90
MB/s) (37.03 MB/s) ... (32.13 MB/s)
read： 85.3 MB/s 85.33 MB/s 78.77MB/s
78.77MB/s (78.77MB/s ) ..... (78.77MB/s )
Hmm, So how can I got a perfect result like this with primary-copy replication?
Thx very much!
Simon
2011/5/9 Simon Tian <[email protected]>:
> 2011/5/9 Gregory Farnum <[email protected]>:
>> On Sun, May 8, 2011 at 7:43 PM, Simon Tian <[email protected]> wrote:
>>> Hi folks,
>>>
>>> I am testing the replication performance of ceph-0.26 with
>>> libceph, write 1G data in with ceph_write() and read it out with
>>> ceph_read(),
>>>
>>> rep_size 1 2
>>> 3 4
>>> write： 78.8 MB/s 39.38 MB/s 27.7 MB/s
>>> 20.90 MB/s
>>> read： 85.3 MB/s 85.33 MB/s 78.77MB/s
>>> 78.77MB/s
>>>
>>> I think if the replication strategy is splay or primary copy, not the
>>> chain, as the thesis said, writing speed for 3, 4 or even more
>>> replication will be a little worse than 2 replication, should be near
>>> with 39.38 MB/s.
>>> But the write performance I got is affect so much by size of replication.
>>>
>>> What is the replication strategy in ceph-0.26, not splay? If splay,
>>> why not near with 39.38 MB/s?
>>>
>>> There is 5 OSDs in 2 hosts, 2 in one and 3 int the other.
>>
>> The replication strategy has been fixed at primary copy for several
>> years now. At expected replication levels (2-3) there just isn't a big
>> difference between the strategies, and limiting it to primary-copy
>> replication makes a lot of the bookkeeping for data safety much easier
>> to handle.
>
> As you know, I am a fresh to ceph, haha
>
> For primary copy, I think when the replication size is 3, 4, or even
> more, the writing speed should also near with 2 replication. Because
> the 2nd, 3rd, 4th, ... replication are written parallelly. The speed
> I got for 3, 4 replication is not near with the speed of 2, in fact,
> like linear reduce.
>
> Thx very much!
>
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