Re: raid5 to raid6 - reshape very slow

["jonathan@infinitedepth.com.au" <jonathan@infinitedepth.com.au>]

I suspected the only move was to wait it out.

Thanks for the feedback Stan & Neil.

On 29/05/2012 5:21 PM, Stan Hoeppner wrote:
> On 5/28/2012 7:56 PM, NeilBrown wrote:
>> On Tue, 29 May 2012 10:33:52 +1000 Jonathan Molyneux
>> <jonathan@infinitedepth.com.au>  wrote:
>>> md1 : active raid6 sde1[0] sdb1[6] sdh1[5] sdc1[4] sdg1[3] sdd1[2] sdf1[1]
>>>         7325679680 blocks super 0.91 level 6, 64k chunk, algorithm 18
>>> [7/6] [UUUUUU_]
>>>         [=========>...........]  reshape = 47.0% (689413888/1465135936)
>>> finish=4126.9min speed=3132K/sec
>> The only thing to do is to wait.  This is very much a seek-bound operation
>> and there is little room for making it go faster.
> With SSDs you'd see the throughput of this operation increase by 2
> orders of magnitude (100x) or more, as SSDs have application level seek
> latency of ~50-80 microseconds, over 100x lower than rotational drives
> which are in the 10-30 millisecond range depending on spindle speed.
>
> Of course, cost/GB for the same total storage is 2 to 10 times higher
> with SSD.  Though interestingly the price of SSDs continues to fall,
> whereas the rotational drive manufacturers are currently keeping drive
> prices artificially high, between 50-100% higher than last year
> depending on drive model, in an effort to recoup apparent financial
> losses caused by the flooding in Thailand.
>