Re: Building RAID5 w/o a Hot Spare

[Carlos Williams <carloswill@gmail.com>]

2010/1/27 Michał Sawicz <michal@sawicz.net>:
> I'm not sure I understand what you want to achieve. A 'spare' disk is
> one that isn't used until any of the other fail, then the spare replaces
> the failed one. The term 'hot spare' is used to identify a disk that is
> a mirror of one of the other drives, but there's no support for that in
> Linux Software-RAID.

I am sorry because I think I was using the wrong terminology then. I
want to use all 4 disks to be an active member or the RAID5 /dev/md0.
I wanted to make sure the command I posted in my original post was not
going to use 3 partitions for active members of RAID5 on /dev/md0 and
use the 4th drive as a 'spare device' in case one of the three drives
fail. I don't want that. I just want 4 active / working devices for
/dev/md0.

>> mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/sda2 /dev/sdb2
>> /dev/sdc2 /dev/sdd2
>
> This will create a RAID5 array of 4 devices, yes. Capacity will be 3 x
> sd?2. Failure of any one of those disks will not harm the data.

OK. I think that answers my questions. Thanks for your help!
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