Bug#474747: mdcfg: Avoid sync fresh created arrays

[Ferenc Wagner <wferi@niif.hu>]

Hi!

First of all, you sent the mail to me only.  I quote your message in
full so that you don't have to resend it.

temnota@kenga.kmv.ru writes:

> On Mon, Apr 07, 2008 at 07:46:17PM +0200, Ferenc Wagner wrote next:
>
>> Andrey Melnikov <temnota@kmv.ru> writes:
>> 
>>> Please, add mdadm '--assume-clean' options when creating new arrays
>>> in installer to avoid initial resync. This make huge speedups when
>>> creating big arrays (100 Gb or more).
>> 
>> While I sympathize, I feel like it isn't the best solution.  You will
>> get a huge mismatch_cnt 
>
> Yet antoher "mars weather device" ? 
> Current algorithm compare all data on disks, empty sectors or dirty sectors,
> and this counter show only internal 'mismatches'.

I don't quite follow you, but if you mean that mismatch_cnt isn't
worth much, I accept that.

>> and lose an initial check of your disks.
>
> 'SECURITY ERASE' by disk controller - very fast, and remap bad sectors if
> found it instead of 'raid fault' detection.

I don't know what you mean, again.
  
>> Isn't is possible/enough to tune /proc/sys/dev/raid/speed_limit_max
>> down for the time of the install?
>
> I'm talk about 'time to wait when raid complete sync zero block's from
> one hdd to antoher'. Tuning speed_limit_max slightly decrase this time.

Why would you have to wait?

> It's possible to add any option to use in 'expert mode' setup ?
-- 
Regards,
Feri.