[CentOS] Re: software raid

Jim Thario jim at thario.net
Thu Mar 29 17:42:13 UTC 2007


Software RAID doesn't care about primary or secondary, as you found out. 
You might care.

The risk is how one of the two drives on a single IDE channel might 
fail. For example, let's say the interface on a drive fails and 
electrically shorts the signals on the cable. This would prevent the 
other working drive from communicating on the channel as well. This has 
never happened to me and it is completely up to your comfort level where 
the redundancy ends.


Manish Kathuria wrote:
> On 3/29/07, tblader <tblader at flambeau.com> wrote:
>> One drawback is software raid wants a single ide device on each ide 
>> channel.
>> This means buying an ide card (if you want more than two devices) 
>> which doesn't
>> always play well with the rest of the system (4+ ide devices).  Some 
>> mainboards
>> might have more than two ide channels, but I just opted for the cheap 
>> ide card.
> Can you please confirm the same or refer to some documentation
> indicating that ? I have recently added two HDDs as the slave devices
> on Primary and Secondary IDE channels configured as software raid
> devices where the two master devices on these IDE channels were
> already being used for  software raid. Now I have 4 devices on two IDE
> channels with partition pairs configured as RAID-1 devices. So far all
> the raid devices are working fine though I do expect a deterioration
> in performance because of 4 devices on two channels.  I would like to
> reconfirm if  "single ide device on each ide channel" is true for
> software raid. Comments please.
> Thanks,

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