Re: [MooseFS-Users] Fwd: CHUNKS_LOOP_MAX_CPS clarification

[Marco M. <mar...@gm...>]

On 05/10/2018 07:34 PM, Gandalf Corvotempesta wrote:
> Clear
> So, CRC testing is almost useless, because one chunk every 10 sec, would need years to fully test a cluster

It is also checked at every read. If the CRC doesn't match,
it will self-heal from the good copy.
So, CRC is not useless. CRC testing is an additional layer of protection
on top of "check CRC on every read". It is not the "only" protection.

-- Marco

> 
> Il ven 11 mag 2018, 00:53 Davies Liu <dav...@gm... <mailto:dav...@gm...>> ha scritto:
> 
>     This loop only check status and goals of chunks, no CRC. CRC is
>     randomly tested by chunk server (1 in every 10 seconds).
> 
>     On Fri, May 11, 2018 at 1:19 AM, Gandalf Corvotempesta
>     <gan...@gm... <mailto:gan...@gm...>> wrote:
>      > Yes, sorry, my mistake but is still impossibile to scan 4.000.000 chunks
>      > checking for CRC, in 300 seconds.
>      >
>      >
>      >
>      > Il gio 10 mag 2018, 18:35 Davies Liu <dav...@gm... <mailto:dav...@gm...>> ha scritto:
>      >>
>      >> max(40, 300) = 300
>      >>
>      >> 2018-05-11 0:17 GMT+08:00 Gandalf Corvotempesta
>      >> <gan...@gm... <mailto:gan...@gm...>>:
>      >> > Il giorno gio 10 mag 2018 alle ore 16:50 Davies Liu
>      >> > <dav...@gm... <mailto:dav...@gm...>>
>      >> > ha scritto:
>      >> >> max(N/CHUNKS_LOOP_MAX_CPS, CHUNKS_LOOP_MIN_TIME)
>      >> >
>      >> > So,
>      >> > N=4000000
>      >> > CHUNKS_LOOP_MAX_CPS = 100000
>      >> > CHUNKS_LOOP_MIN_TIME = 300
>      >> >
>      >> > to scan 4.000.000 chunks, I need
>      >> >
>      >> > max(4000000/100000, 300) = 40 seconds ?
>      >> >
>      >> > That's impossible.
>      >>
>      >>
>      >>
>      >> --
>      >>  - Davies
> 
> 
> 
>     -- 
>       - Davies
> 
> 
> 
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