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Adrian Sevcenco 08-23-2012 09:49 AM

Order of sata/sas raid cards
 
On 08/23/12 12:13, Jobst Schmalenbach wrote:
> Is there a way to tell the kernel in which order to load the drives
> and assign the drive order in a way that the new drives are assigned
> SDC and SDD and the old drives get SDA and SDB?
use UUID= in fstab (lsblk -o NAME,KNAME,UUID) and you will get rid of
all this headaches (if you have software raid the assembling is done
internally based on UUID so you don't have to worry about mdraid)

HTH,
Adrian

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Jobst Schmalenbach 08-23-2012 12:01 PM

Order of sata/sas raid cards
 
Hi Adrian

yes this will do.
Because I do not know (yet) the UUID of the new partitions (drives),
if I specify the UUID for the known drives for the partitions
the kernel will assign the new drives to higher sdx?
Is this correct?

thanks
Jobst



On Thu, Aug 23, 2012 at 12:49:38PM +0300, Adrian Sevcenco (Adrian.Sevcenco@cern.ch) wrote:
> On 08/23/12 12:13, Jobst Schmalenbach wrote:
> > Is there a way to tell the kernel in which order to load the drives
> > and assign the drive order in a way that the new drives are assigned
> > SDC and SDD and the old drives get SDA and SDB?
> use UUID= in fstab (lsblk -o NAME,KNAME,UUID) and you will get rid of
> all this headaches (if you have software raid the assembling is done
> internally based on UUID so you don't have to worry about mdraid)
>
> HTH,
> Adrian
>


> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos


--
f u cn rd ths, u cn gt a gd jb n cmptr prgmmng. [Anon]

| |0| | Jobst Schmalenbach, jobst@barrett.com.au, General Manager
| | |0| Barrett Consulting Group P/L & The Meditation Room P/L
|0|0|0| +61 3 9532 7677, POBox 277, Caulfield South, 3162, Australia
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Markus Falb 08-23-2012 12:19 PM

Order of sata/sas raid cards
 
On 23.8.2012 14:01, Jobst Schmalenbach wrote:
> Hi Adrian
>
> yes this will do.
> Because I do not know (yet) the UUID of the new partitions (drives),
> if I specify the UUID for the known drives for the partitions
> the kernel will assign the new drives to higher sdx?
> Is this correct?

After reboot sdx could be sdy, as you noticed.
The solution: you dont access a drive via /dev/sdx
You access per UUID and the kernel maps it to the appropiate sdXY which
could be sdy after reboot.

I am not sure about initial ramdisks etc. maybe there is hardcoded stuff
to sdx in there. Maybe it has to be rebuilt? Maybe you has to rebuild
initrd as well as updating fstab?
--
Kind Regards, Markus Falb

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08-23-2012 01:40 PM

Order of sata/sas raid cards
 
Markus Falb wrote:
> On 23.8.2012 14:01, Jobst Schmalenbach wrote:
>> Hi Adrian
>>
>> yes this will do.
>> Because I do not know (yet) the UUID of the new partitions (drives),
>> if I specify the UUID for the known drives for the partitions
>> the kernel will assign the new drives to higher sdx?
>> Is this correct?
>
> After reboot sdx could be sdy, as you noticed.
> The solution: you dont access a drive via /dev/sdx
> You access per UUID and the kernel maps it to the appropiate sdXY which
> could be sdy after reboot.

You can also label it. I loathe UUIDs - there is *no* way you're going to
remember one when you need it. Labels are so much clearer.
>
> I am not sure about initial ramdisks etc. maybe there is hardcoded stuff
> to sdx in there. Maybe it has to be rebuilt? Maybe you has to rebuild
> initrd as well as updating fstab?

I've actually never seen a system *not* know what the first drive was,
hardware-wise. And grub will point to root hd(0,x), normally, not UUID or
anything else. You *can* (and I do, all the time) use LABEL= on the kernel
line.

mark

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Adrian Sevcenco 08-23-2012 02:09 PM

Order of sata/sas raid cards
 
On 08/23/12 15:01, Jobst Schmalenbach wrote:
> Hi Adrian
Hi!

> yes this will do.
> Because I do not know (yet) the UUID of the new partitions (drives),
> if I specify the UUID for the known drives for the partitions
> the kernel will assign the new drives to higher sdx?
AFAIK the sdX names are given by the bios so this is why when new
hardware is addend and/or something is change hardware-wise the sdX
nomenclature is changed.
If you decide to use UUID nomenclature you should use it for ALL
disks/partitions .. for centos that menas the beside fstab to modify
grub to have something like root=UUID= in kernel command line from grub.
IMHO the easiest way to change all to UUID is to boot a live-cd find out
all UUIDs and modify the fstab and grub accordingly.
I dont know about root(hd0,0) .. i have the grub and / installed on an
disk which by system is recognized as /dev/sdc and in grub.conf i have
hd(2,msdos1)

HTH,
Adrian


> Is this correct?
>
> thanks
> Jobst
>
>
>
> On Thu, Aug 23, 2012 at 12:49:38PM +0300, Adrian Sevcenco (Adrian.Sevcenco@cern.ch) wrote:
>> On 08/23/12 12:13, Jobst Schmalenbach wrote:
>>> Is there a way to tell the kernel in which order to load the drives
>>> and assign the drive order in a way that the new drives are assigned
>>> SDC and SDD and the old drives get SDA and SDB?
>> use UUID= in fstab (lsblk -o NAME,KNAME,UUID) and you will get rid of
>> all this headaches (if you have software raid the assembling is done
>> internally based on UUID so you don't have to worry about mdraid)
>>
>> HTH,
>> Adrian
>>
>
>
>> _______________________________________________
>> CentOS mailing list
>> CentOS@centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>
>


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08-23-2012 02:24 PM

Order of sata/sas raid cards
 
Adrian Sevcenco wrote:
> On 08/23/12 15:01, Jobst Schmalenbach wrote:
<snip>
> I dont know about root(hd0,0) .. i have the grub and / installed on an
> disk which by system is recognized as /dev/sdc and in grub.conf i have
> hd(2,msdos1)
<snip>
I've never seen anything like msdos1 - I assume it's a label, but have
seen nothing suggesting I could do that. At any rate, that's h/d 3, or
presented as the third drive to the BIOS?

mark


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08-23-2012 02:41 PM

Order of sata/sas raid cards
 
Adrian Sevcenco wrote:
> On 08/23/12 15:01, Jobst Schmalenbach wrote:
<snip>
> I dont know about root(hd0,0) .. i have the grub and / installed on an
> disk which by system is recognized as /dev/sdc and in grub.conf i have
> hd(2,msdos1)
>
Ok... to follow myself up, I started looking. There is zero indication in
any manpage about the syntax you use. After doing some googling, I finally
found
<http://www.gnu.org/software/grub/manual/grub.html#Device-syntax>, and
geez, the Gnu documentation is *dreadful* - why isn't there a syntax
description for the root line of a grub entry? Then I found the above,
which is *not* with the root directive, and they give examples including
msdos1, msdos5, but with no explanation of what those names are - labels?
the first and fifth partitions that are msdos format?

As I said in my previous post, I've never seen anything like that - it's
always
root (hdx,y).

mark


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Adrian Sevcenco 08-23-2012 02:51 PM

Order of sata/sas raid cards
 
On 08/23/12 17:41, m.roth@5-cent.us wrote:
> Adrian Sevcenco wrote:
>> On 08/23/12 15:01, Jobst Schmalenbach wrote:
> <snip>
>> I dont know about root(hd0,0) .. i have the grub and / installed on an
>> disk which by system is recognized as /dev/sdc and in grub.conf i have
>> hd(2,msdos1)
>>
> Ok... to follow myself up, I started looking. There is zero indication in
> any manpage about the syntax you use. After doing some googling, I finally
> found
> <http://www.gnu.org/software/grub/manual/grub.html#Device-syntax>, and
> geez, the Gnu documentation is *dreadful* - why isn't there a syntax
> description for the root line of a grub entry? Then I found the above,
> which is *not* with the root directive, and they give examples including
> msdos1, msdos5, but with no explanation of what those names are - labels?
> the first and fifth partitions that are msdos format?
>
> As I said in my previous post, I've never seen anything like that - it's
> always
> root (hdx,y).
err, sorry that was my mistake ... i copy pasted from wrong terminal
(from my desktop fedora 16 grub 2 instead from the centos server where i
look initially)

so, to wrap things up: on my centos 5 storage i have root (hd0,0)
that stayed the same no matter how many block devices i added or removed
from my hardware card... but in fstab i use only UUIDs

HTH,
Adrian


>
> mark
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>


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08-23-2012 02:57 PM

Order of sata/sas raid cards
 
Adrian Sevcenco wrote:
> On 08/23/12 17:41, m.roth@5-cent.us wrote:
>> Adrian Sevcenco wrote:
>>> On 08/23/12 15:01, Jobst Schmalenbach wrote:
>> <snip>
>>> I dont know about root(hd0,0) .. i have the grub and / installed on an
>>> disk which by system is recognized as /dev/sdc and in grub.conf i have
>>> hd(2,msdos1)
>>>
>> Ok... to follow myself up, I started looking. There is zero indication
>> in any manpage about the syntax you use. After doing some googling, I
>> finally found
>> <http://www.gnu.org/software/grub/manual/grub.html#Device-syntax>, and
>> geez, the Gnu documentation is *dreadful* - why isn't there a syntax
>> description for the root line of a grub entry? Then I found the above,
>> which is *not* with the root directive, and they give examples including
>> msdos1, msdos5, but with no explanation of what those names are -
>> labels? the first and fifth partitions that are msdos format?
>>
>> As I said in my previous post, I've never seen anything like that - it's
>> always
>> root (hdx,y).
> err, sorry that was my mistake ... i copy pasted from wrong terminal
> (from my desktop fedora 16 grub 2 instead from the centos server where i
> look initially)

Oh, no problem. I can't see how you could *possibly* have copied from the
wrong term (says the guy with seven open for use, sudo -s on three, and
one for later use for streaming media....)
>
> so, to wrap things up: on my centos 5 storage i have root (hd0,0)
> that stayed the same no matter how many block devices i added or removed
> from my hardware card... but in fstab i use only UUIDs

Yup, what we've got. As I said, though, I hate UUIDs - for any non-RAIDed
drives, we *always* label them, indicative of where they mount. That way,
we all know what's expected, where a UUID tells you nothing of what it is.

mark

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Jobst Schmalenbach 08-23-2012 11:15 PM

Order of sata/sas raid cards
 
I agree with the UUID stuff, I do not like them for the exact same reason.
I do not understand why RedHat cannot include the partition into the UUID,
e.g.

dev-sda1-c05e-449a-837b-b2579b949d55

As for the first drive, when the kernel boots I think it assigns the
drives in order of the controller on the system bus/slots. As the new controller
sits lower in the slot system (i.e. closer to the CPUs) it is recognised first as
I can see it appearing first in the order being initialized by the kernel.
I cant move it below the old card as there is no slot that has the correct PCI-x8.

I will try the LABEL way of doing ....

I remember that was the same problem a few years back when one had multiple
network interfaces .... until the MAC addresses where introduced into the ifcfg files.

Jobst



On Thu, Aug 23, 2012 at 09:40:24AM -0400, m.roth@5-cent.us (m.roth@5-cent.us) wrote:
> Markus Falb wrote:
> > On 23.8.2012 14:01, Jobst Schmalenbach wrote:
> >> Hi Adrian
> >>
> >> yes this will do.
> >> Because I do not know (yet) the UUID of the new partitions (drives),
> >> if I specify the UUID for the known drives for the partitions
> >> the kernel will assign the new drives to higher sdx?
> >> Is this correct?
> >
> > After reboot sdx could be sdy, as you noticed.
> > The solution: you dont access a drive via /dev/sdx
> > You access per UUID and the kernel maps it to the appropiate sdXY which
> > could be sdy after reboot.
>
> You can also label it. I loathe UUIDs - there is *no* way you're going to
> remember one when you need it. Labels are so much clearer.
> >
> > I am not sure about initial ramdisks etc. maybe there is hardcoded stuff
> > to sdx in there. Maybe it has to be rebuilt? Maybe you has to rebuild
> > initrd as well as updating fstab?
>
> I've actually never seen a system *not* know what the first drive was,
> hardware-wise. And grub will point to root hd(0,x), normally, not UUID or
> anything else. You *can* (and I do, all the time) use LABEL= on the kernel
> line.
>
> mark
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos

--
When the Pope visits a country he really likes, does he french kiss the ground?????????

| |0| | Jobst Schmalenbach, jobst@barrett.com.au, General Manager
| | |0| Barrett Consulting Group P/L & The Meditation Room P/L
|0|0|0| +61 3 9532 7677, POBox 277, Caulfield South, 3162, Australia
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