Hi,
I was just talking to Chance Reschke through e-mail about "mkraid" with the
raid-0 personality. He states that you do have to use the "mkraid" command
on the raid-0 arrays, even though the "documentation" says that you don't.
Here is what he wrote:
Chance Reschke [mailto:[EMAIL PROTECTED]] wrote:
> The documentation - what there is of it - states that you shouldn't use
> mkraid with raid-0 arrays. It says you should just run 'raidstart -a' (or
> alternately, 'raidstart /dev/md0'), and presto, your array is initialized
> and running, all in one easy step. This is wrong. I had to run 'mkraid
> /dev/md0'. Strangely, 'raidstart -a' works, but 'raidstop -a' doesn't. I
> have to use 'raidstop /dev/md0'.
My reply to him was the following:
David Harris [mailto:[EMAIL PROTECTED]] wrote:
> Don't trust any of the "documentation" you find except for the
> "RAID5.HOWTO" file. I learned that the hard way.
>
> I believe that the 0.90 kernel driver wants to see a superblock on the
> raid-0 device, because it uses it in the autostart. Otherwise, there is
> really no need for a superblock on raid-0, because the device is
> always in sync.
Also, beware of the weird "error messages" that mkraid emits. They are not
really to the point and sometimes don't even seem like error messages. For
example, I had it say "invalid superblock on device XXX" when I didn't have
a chunk-size in /etc/raidtab for my raid-1 device. Source code is the real
documentation on anything relating to mkraid, or the raid drivers.
About the documentation, most of it is from the previous version of the
kernel raid drivers and raidtools. If you are reading anything that mentions
running "mdadd", "mdstart", and "mdstop" it is talking about this older
version. Whatever it says probably does not work with the 0.90 version. They
are vastly different.
I think the "no mkraid with raid-0" mis-conception is a symptom of the old
documentation. That was true with the older version. However, the 0.90
version requires a superblock on the raid-0 array.
- David Harris
Principal Engineer, DRH Internet Services
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of Roberto Rivera
Sent: Friday, December 18, 1998 11:26 PM
To: David Harris
Cc: Roberto Rivera; [EMAIL PROTECTED]
Subject: RE: Raidtools-0.90
Well I am trying to create a striped(raid 0) raid drive. I read in the
document and man page that mkraid can't be used for striped drives. Is
there some other step required? Thanks for such a quick reply.
Robert
