raidstart used deprecated START_ARRAY ioctl

raidstart used deprecated START_ARRAY ioctl

[Norberto Bensa]

Hello,

What does this mean and how do I fix it? 

md: raidstart(pid 4983) used deprecated START_ARRAY ioctl. This will not be 
supported beyond 2.6

Thanks,
Norberto

Re: raidstart used deprecated START_ARRAY ioctl

[Neil Brown]

On Friday July 9, norberto+linux-kernel@bensa.ath.cx wrote:
> Hello,
> 
> What does this mean and how do I fix it? 
> 
> md: raidstart(pid 4983) used deprecated START_ARRAY ioctl. This will not be 
> supported beyond 2.6
> 

It means that the mechanism (that START_ARRAY ioctl) that 'raidstart'
uses to start an array is "deprecated", as in it won't be supported in
future. 
The reason for this is that it is badly designed and is not reliable.
If you have a degraded array, there is at-least and even chance that
raidstart will not successfully start it for you.

So, you should stop using raidstart.

The options are:

 1/ use "autodetect".  I'm not a big fan of this personally, but it is
   much more reliable than START_ARRAY.
   This is done by set the partition type of all partitions that
   contain part of an MD array to "Linux Raid Autodetect" (0xFD).
   Then all arrays are found and assembled at boot time.
   This requires having all of md (that you need) compiled into the
   kernel, not as modules.

 2/ use mdadm.  Read the man page about ASSEMBLE MODE.
    You have  an /etc/mdadm.conf that lists 
      - devices (or partitions) to scan
      - arrays to be started
      -  UUID of each array

    and mdadm will find and assemble the arrays.

NeilBrown

Re: raidstart used deprecated START_ARRAY ioctl

[Norberto Bensa]

Hello Neil,

Neil Brown wrote:
> On Friday July 9, norberto+linux-kernel@bensa.ath.cx wrote:
> > Hello,
> >
> > What does this mean and how do I fix it?
>
> If you have a degraded array, there is at-least and even chance that
> raidstart will not successfully start it for you.

Aha. It didn't start the array when I compiled md and raid0 built-in; that's 
how I discovered this.

It works as modules (weird to me, but I'm not a kernel guru)

> So, you should stop using raidstart.

Ok.

> The options are:
>
>  1/ use "autodetect".  I'm not a big fan of this personally, but it is
>    much more reliable than START_ARRAY.

I already have. But Gentoo uses raidstart (This is pure guessing, I need to 
dig into the init scripts.

>    This is done by set the partition type of all partitions that
>    contain part of an MD array to "Linux Raid Autodetect" (0xFD).
>    Then all arrays are found and assembled at boot time.
>    This requires having all of md (that you need) compiled into the
>    kernel, not as modules.

Did I get that right? Can I get rid of raidstart and the array will be 
"assembled by the kernel"?

>  2/ use mdadm.  Read the man page about ASSEMBLE MODE.
>     You have  an /etc/mdadm.conf that lists
>       - devices (or partitions) to scan
>       - arrays to be started
>       -  UUID of each array
>
>     and mdadm will find and assemble the arrays.

I think I have read something about mdadm in Gentoo docs somewhere. I really 
need to check that out.

Thanks Neil.

Best regards,
Norberto

Re: raidstart used deprecated START_ARRAY ioctl

[Neil Brown]

On Friday July 9, norberto+linux-kernel@bensa.ath.cx wrote:
> 
> >    This is done by set the partition type of all partitions that
> >    contain part of an MD array to "Linux Raid Autodetect" (0xFD).
> >    Then all arrays are found and assembled at boot time.
> >    This requires having all of md (that you need) compiled into the
> >    kernel, not as modules.
> 
> Did I get that right? Can I get rid of raidstart and the array will be 
> "assembled by the kernel"?

Yes.  If all the components of the arrays are in partitions with type
0xFD, and the md driver and raid personalities are compiled into the
kernel (not modules), then the kernel will automatically start the
arrays for you.

NeilBrown

Re: raidstart used deprecated START_ARRAY ioctl

[Norberto Bensa]

Neil Brown wrote:
> On Friday July 9, norberto+linux-kernel@bensa.ath.cx wrote:
> > Did I get that right? Can I get rid of raidstart and the array will be
> > "assembled by the kernel"?
>
> Yes.  If all the components of the arrays are in partitions with type
> 0xFD, and the md driver and raid personalities are compiled into the
> kernel (not modules), then the kernel will automatically start the
> arrays for you.

Thanks Neil!!

Actually, after I sent that e-mail, I tried it myself and it worked like a 
charm.

With best regards,
Norberto