Re: Resize on dirty array?

[James Peverill <jamespev@net1plus.com>]

The resize went fine, but after re-adding the drive back into the array 
I got another fail event (on another drive) about 23% through the 
rebuild :(

Did I have to "remove" the bad drive before re-adding it with mdadm?  I 
think my array might be toast...

Any tips on where I should go now?

Thanks for the help.

James


Neil Brown wrote:
> On Monday August 7, jamespev@net1plus.com wrote:
>   
>> I have a software raid 5 setup with four drives.  One drive failed.  I 
>> got a replacement but unfortunately it turns out that my original disks 
>> were just a few gigs over the replacement.  It seems that most 
>> manufacturers don't actually advertise the REAL capacity of the disk, so 
>> getting one that is the same size as the old ones could be tough.(and 
>> they aren't available anymore of course...)
>>
>> So my question... can I resize the array while it is missing a drive?  
>> The raid is <50% full, and the few gigs is only a few percent.  In 
>> retrospect I shouldn't have sized them right to the limit...
>>     
>
> Yes, that should work.
>
> First resize the filesystem to make it smaller.
> Then resize the array
>   mdadm --grow /dev/mdX --size=whatever
>
> You have to calculate 'whatever' yourself.  It is in kibibytes and
> must be 128K < size of new drive, and obviously must leave room for
> the filesystem.
>
> A good suggestion is:
>   shrink the filesystem a lot.
>   shrink the array an adequate amount
>   add the new drive
>   resize the array up to 'max'  (mdadm -G /dev/mdX --size=max)
>   resize the filesystem up to max.
>
> NeilBrown
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