Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Tru Huynh]

Hi,

It's all in the documentation from Red Hat.

kickstart snip 
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Installation_Guide/sect-kickstart-examples.html

manual partitionning
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Installation_Guide/sect-disk-partitioning-setup-x86.html#sect-custom-partitioning-x86
scroll down to  ⁠ 6.14.4.2. Create Software RAID

ymmv, 

Tru
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Eugene Poole]

First let me say I am not a true expert, but I am experienced.

If this machine you purchased was some name brand, you must be speaking 
about hardware raid, true? If this is true, it normally presents you 
with what looks like a standard drive (/dev/sda) for every 2 drives 
configured as raid-1. Also, most name brand servers give you a bootable 
machine day one.


If you are using software raid, you must have configured it yourself.  
Here is what my custom machine has:


2 - 120 GB SSD

2 - 4 TB spinning drives

During my CentOS 7 install is where I performed the software raid-1 
configuration. I never do the default partition configuration so here is 
my setup (used fdisk -l):


Disk /dev/sda: 120.0 GB, 120034123776 bytes, 234441648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0001d7e8

   Device Boot  Start End  Blocks   Id  System
/dev/sda12048   13460479967301376   fd  Linux raid 
autodetect
/dev/sda2   134604800   18475212725073664   fd  Linux raid 
autodetect
/dev/sda3   184752128   23319142324219648   fd  Linux raid 
autodetect

/dev/sda4   233191424   234440703  6246405  Extended
/dev/sda5   *   233195520   234440703  622592   fd  Linux raid 
autodetect


Disk /dev/sdb: 120.0 GB, 120034123776 bytes, 234441648 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x85a6

   Device Boot  Start End  Blocks   Id  System
/dev/sdb12048   13460479967301376   fd  Linux raid 
autodetect
/dev/sdb2   134604800   18475212725073664   fd  Linux raid 
autodetect
/dev/sdb3   184752128   23319142324219648   fd  Linux raid 
autodetect

/dev/sdb4   233191424   234440703  6246405  Extended
/dev/sdb5   *   233195520   234440703  622592   fd  Linux raid 
autodetect


Disk /dev/sdc: 4000.8 GB, 4000787030016 bytes, 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: gpt


# Start  EndSize  TypeName
 1 2048   1699579903  810.4G  Linux RAID
 2   1699579904   3399157759  810.4G  Linux RAID
 3   3399157760   3911510015  244.3G  Linux RAID
 4   3911510016   5611087871  810.4G  Linux RAID

Disk /dev/sdd: 4000.8 GB, 4000787030016 bytes, 7814037168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk label type: gpt


# Start  EndSize  TypeName
 1 2048   1699579903  810.4G  Linux RAID
 2   1699579904   3399157759  810.4G  Linux RAID
 3   3399157760   3911510015  244.3G  Linux RAID
 4   3911510016   5611087871  810.4G  Linux RAID

My df -h display shows me the following:

/dev/md126  583M   317M   224M   59%   /boot

I have basically the definitions using CentOS 6 and CentOS 7 and it's my 
understanding you must have a /boot device.  Also during installation of 
CentOS 7 when writing the MBR to the MD device (in my case md126) it 
writes the information to both sda and sdb. With CentOS 6, according to 
HowToForge there are extra steps required to get the MBR on both sda and 
sdb.


I have not had to replace either of these SSD, but I have had to replace 
spinning drives on my CentOS 6 machines in the past.


Gene


On 1/26/2017 7:00 AM, centos-requ...@centos.org wrote:


No. Brand new machine, pulled it out of the box and racked it. NOTHING on the
internal SSDs. Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No
partitions, nothing. However, when I bring it up, fdisk shows an MBR with no
partitions. I can, however, mount /dev/md127p3 as /mnt/sysimage, and all is 
there.

Did I need to make a single partition, on each drive, and then make the RAID 1
out of *those*? I don't think I need to have /boot not on a RAID.

mark



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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Tony Mountifield]

In article <5ef97952-14c0-6ad2-0803-c24691a68...@gmail.com>,
Gordon Messmer  wrote:
> On 01/26/2017 01:40 AM, Tony Mountifield wrote:
> > Anaconda doesn't set up the boot sector on the second drive by default,
> > so I put some grub commands in the post-install section of kickstart
> > to do so.
> 
> 
> I can't attest that it *works* (mostly since I use UEFI everywhere 
> possible) but anaconda definitely attempts to install grub on each drive 
> with a copy of /boot:
> 
> https://github.com/rhinstaller/anaconda/blob/master/pyanaconda/bootloader.py

Thanks, that's interesting to know. When I first started doing this it was on
CentOS 4, and I'm pretty sure the second drive didn't get grubbed back then,
which would be what prompted me to add the post-install grub for the second
drive at that time.

I never went back to check whether the need had been obviated in CentOS 5 or 6.

Cheers
Tony
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Gordon Messmer]

On 01/26/2017 01:40 AM, Tony Mountifield wrote:

Anaconda doesn't set up the boot sector on the second drive by default,
so I put some grub commands in the post-install section of kickstart
to do so.



I can't attest that it *works* (mostly since I use UEFI everywhere 
possible) but anaconda definitely attempts to install grub on each drive 
with a copy of /boot:


https://github.com/rhinstaller/anaconda/blob/master/pyanaconda/bootloader.py

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Tony Mountifield]

In article <1485416344.2047.1.ca...@biggs.org.uk>,
Pete Biggs  wrote:
> 
> > 
> > If you are using RAID 1 kernel mirroring, you can do that with /boot too,
> > and Grub finds the kernel just fine. I've done it many times:
> > 
> > 
> Hmm, OK. I wonder why anaconda doesn't do it then.
> 
> Reading various websites, it looks like grub2 can do it, but you have
> to make sure that various grub modules are installed first - i.e. do
> something like 
> 
>   grub-install --modules='biosdisk ext2 msdos raid mdraid' /dev/xxx
> 
> I don't know if they are added by default these days.

I don't know, but I've never had to do it, when using plain mirroring,
on either C4, C5 or C6.  I can imagine you would need to if /boot was
RAID 0 striped, if indeed that is even possible.

> The other gotcha is, of course, that the boot sectors aren't RAID'd -
> so if /dev/sda goes, replacing it will make the system unbootable since
> it doesn't contain the boot sectors. Hot swap will keep the system
> running but you have to remember to re-install the correct boot sector
> before reboot. If you have to bring the machine down to change the
> disk, then things could get interesting!

Yup, been there, done that. So long as you use grub to install the boot
sector on both drives, then you can always tell the BIOS to boot from
the other drive to bring the system up after replacing the first disk.

Anaconda doesn't set up the boot sector on the second drive by default,
so I put some grub commands in the post-install section of kickstart
to do so.

Cheers
Tony
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Work: t...@softins.co.uk - http://www.softins.co.uk
Play: t...@mountifield.org - http://tony.mountifield.org
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Pete Biggs]

> 
> If you are using RAID 1 kernel mirroring, you can do that with /boot too,
> and Grub finds the kernel just fine. I've done it many times:
> 
> 
Hmm, OK. I wonder why anaconda doesn't do it then.

Reading various websites, it looks like grub2 can do it, but you have
to make sure that various grub modules are installed first - i.e. do
something like 

  grub-install --modules='biosdisk ext2 msdos raid mdraid' /dev/xxx

I don't know if they are added by default these days.

The other gotcha is, of course, that the boot sectors aren't RAID'd -
so if /dev/sda goes, replacing it will make the system unbootable since
it doesn't contain the boot sectors. Hot swap will keep the system
running but you have to remember to re-install the correct boot sector
before reboot. If you have to bring the machine down to change the
disk, then things could get interesting!

P.
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Rob Kampen]

On 26/01/17 05:46, Tony Mountifield wrote:

In article <1485342377.3072.6.ca...@biggs.org.uk>,
Pete Biggs  wrote:

On Tue, 2017-01-24 at 17:14 -0500, m.r...@5-cent.us wrote:

So, it installed happily.

Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
grub2-install.

Um, nope. I edited the device map from hd0 and hd1 being the RAID to
/dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
identify the filesystem on hd0, and can't perform a safety check, and
gives up.

What am I missing? Google is not giving me any answers


Surely, if you are using software RAID, then you should configure that
RAID in anaconda, that will then cope with setting up the partitions to
allow booting.  Basically it needs a small non-RAID partition to hold
/boot on the boot disk.

Remember that the boot sequence is generally: BIOS reads MBR and
executes it; MBR code reads kernel from /boot and executes it (yes,
it's more complicated than that). If the MBR code doesn't know how to
read a RAID partition, then it's going to fail, that's why you have a
small non-RAID partition to hold /boot.

Hardware RAID is different because it interfaces at the BIOS level so
the MBR code doesn't need to know how to specifically read it.

If you are using RAID 1 kernel mirroring, you can do that with /boot too,
and Grub finds the kernel just fine. I've done it many times:

1. Primary partition 1 type FD, size 200M. /dev/sda1 and /dev/sdb1.

I think it wiser to have /boot at 1Gb nowadays.

2. Create /dev/md0 as RAID 1 from /dev/sda1 and /dev/sdb1.
3. Assign /dev/md0 to /boot, ext3 format (presumably ext4 would work too?)
4. Make sure to setup both drives separately in grub.

Typically I then go on to have /dev/sda2+/dev/sdb2 => /dev/md1 => swap,
and /dev/sda3+/dev/sdb3 => /dev/md2 => /

Cheers
Tony


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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[m . roth]

Gordon Messmer wrote:
> You didn't answer all of the questions I asked, but I'll answer as best
> I can with the information you gave.
>
Manitu ate my email, *again*.

> On 01/25/2017 04:47 AM, mark wrote:
>>
>> Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No partitions,
>> nothing.
>
> OK, so right off the bat we have to note that this is not a
> configuration supported by Red Hat.  It is possible to set such a system
> up, but it may require advanced knowledge of grub2 and mdadm.  Because

> I sympathize.  I wanted to use full disk RAID, too.  I thought that

Thank you.
>
>> However, when I bring it up, fdisk shows an MBR with no partitions. I
>> can, however, mount /dev/md127p3 as /mnt/sysimage, and all is there.
>
> I assume you're booting with BIOS, then?

Yup.
>
> One explanation for fdisk showing nothing is that you're using GPT
> instead of MBR (I think).  In order to boot on such a system, you'd need

Nope. fdisk sees it as an MBR. The SSDs are only 128G. They just run the
server, and the LSI card takes care of the 12 hot-swap drives 
(It's a storage server.)

> a bios_boot partition at the beginning of the RAID volume to provide
> enough room for grub2 not to stomp on the first partition with a
> filesystem.
>
> The other explanation that comes to mind is that you're using an mdadm
> metadata version stored at the beginning of the drive instead of the
> end.  Do you know what metadata version you used?

I took CentOS 7's default for mdadm.
>
>> Did I need to make a single partition, on each drive, and then make
>> the RAID 1 out of *those*? I don't think I need to have /boot not on a
>> RAID.
>
> That's one option, but it still won't be a supported configuration.

Yeah, I see. Well, time to go rebuild, and this time with three separate
RAID 1 partitions

mark

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Gordon Messmer]

You didn't answer all of the questions I asked, but I'll answer as best 
I can with the information you gave.


On 01/25/2017 04:47 AM, mark wrote:


Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No partitions, 
nothing.


OK, so right off the bat we have to note that this is not a 
configuration supported by Red Hat.  It is possible to set such a system 
up, but it may require advanced knowledge of grub2 and mdadm.  Because 
the vendor doesn't support this configuration, and as you've seen, the 
tools don't always parse out the information they need, you'll forever 
be responsible for fixing any boot problems that come up.  Do you really 
want that?


I sympathize.  I wanted to use full disk RAID, too.  I thought that 
replacing disks would be much easier this way, since there'd just be one 
md RAID device to manage.  That was an attractive option after working 
with hardware RAID controllers that were easy to manage but expensive, 
unreliable, and performed very poorly in some conditions.  But after a 
thorough review, I found my earlier suggestion of partitioned RAID with 
the kickstart and RAID management script I provided was the least work 
for me, in the long term.


However, when I bring it up, fdisk shows an MBR with no partitions. I 
can, however, mount /dev/md127p3 as /mnt/sysimage, and all is there.


I assume you're booting with BIOS, then?

One explanation for fdisk showing nothing is that you're using GPT 
instead of MBR (I think).  In order to boot on such a system, you'd need 
a bios_boot partition at the beginning of the RAID volume to provide 
enough room for grub2 not to stomp on the first partition with a filesystem.


The other explanation that comes to mind is that you're using an mdadm 
metadata version stored at the beginning of the drive instead of the 
end.  Do you know what metadata version you used?


Did I need to make a single partition, on each drive, and then make 
the RAID 1 out of *those*? I don't think I need to have /boot not on a 
RAID.



That's one option, but it still won't be a supported configuration.

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Tony Mountifield]

In article <1485342377.3072.6.ca...@biggs.org.uk>,
Pete Biggs  wrote:
> On Tue, 2017-01-24 at 17:14 -0500, m.r...@5-cent.us wrote:
> > So, it installed happily.
> > 
> > Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
> > grub2-install.
> > 
> > Um, nope. I edited the device map from hd0 and hd1 being the RAID to
> > /dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
> > identify the filesystem on hd0, and can't perform a safety check, and
> > gives up.
> > 
> > What am I missing? Google is not giving me any answers
> > 
> 
> Surely, if you are using software RAID, then you should configure that
> RAID in anaconda, that will then cope with setting up the partitions to
> allow booting.  Basically it needs a small non-RAID partition to hold
> /boot on the boot disk.
> 
> Remember that the boot sequence is generally: BIOS reads MBR and
> executes it; MBR code reads kernel from /boot and executes it (yes,
> it's more complicated than that). If the MBR code doesn't know how to
> read a RAID partition, then it's going to fail, that's why you have a
> small non-RAID partition to hold /boot.
> 
> Hardware RAID is different because it interfaces at the BIOS level so
> the MBR code doesn't need to know how to specifically read it.

If you are using RAID 1 kernel mirroring, you can do that with /boot too,
and Grub finds the kernel just fine. I've done it many times:

1. Primary partition 1 type FD, size 200M. /dev/sda1 and /dev/sdb1.
2. Create /dev/md0 as RAID 1 from /dev/sda1 and /dev/sdb1.
3. Assign /dev/md0 to /boot, ext3 format (presumably ext4 would work too?)
4. Make sure to setup both drives separately in grub.

Typically I then go on to have /dev/sda2+/dev/sdb2 => /dev/md1 => swap,
and /dev/sda3+/dev/sdb3 => /dev/md2 => /

Cheers
Tony
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Work: t...@softins.co.uk - http://www.softins.co.uk
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Valeri Galtsev]

On Wed, January 25, 2017 9:51 am, m.r...@5-cent.us wrote:
> Let me see if I can, um, reboot this thread
>
> I made a RAID 1 of two raw disks, /dev/sda and /dev/sdb, *not* /dev/sdax
> /dev/sdbx. Then I installed CentOS 7 on the RAID, with /boot, /, and swap
> being partitions on the RAID. My problem is that grub2-install absolutely
> and resolutely refuses to install on /dev/sda or /dev/sdb.
>
> I've currently got it up in a half-assed rescue mode, and have mount -o
> bind /dev, /proc/ and /sys under /mnt/sysimage, and chrooted there. That's
> where I'm trying to do my grub2-install.
>
> So:
>   1. *Is* there space for grub2 to install the bootloader under where the
> mdadm starts?

To the best of my knowledge: no. To have mdadm started (md devices
created) you already need kernel loaded, at this stage you don't have it,
you will have it in memory after you load initramdrive, so initramdrive is
useless on md devices which do not exist yet at the moment you load
initramdrive.

> Or do I have to partition the disks (/dev/sda1 100%, ditto
> /dev/sdb1, then
> create the RAID 1 with the partitions, and *then* grub2-install?

Not necessarily, you can have software RAID/mirror of /dev/sda /dev/sdb
(without those having disk labels).

However, to boot you need regular drive partition present that hosts /boot
(and bootloader somewhere on drive that does have disk label). You can
have it all on separate tiny drive.

Several years back it was done as I and one more poster described in the
tread before the thread was "rebooted". Now it is possible grub progressed
since, but I doubt that grub supports Linux software RAID devices, for
which it would need appropriate Linux portion of code, which is rather
large, and GRUB being used to boot other system as well then likely will
need to have their implementations of the same... But that might be
outdated, I hope someone with current knowledge will chime in.

Valeri

>   2. I *think* that one thing that grub2-install is complaining about is
> that it can't
>find /boot/grub2. I've tried doing it with
> $  grub2-install --boot-directory=/boot /dev/sda
>and
> $  grub2-install --boot-directory=/dev/md127p1/ /dev/sda
>and
> $  grub2-install --boot-directory=/dev/md127pw/boot /dev/sda
>and it tells me it cannot find the canonical path for the grub2
> directory. Is
>there some way to specify where it should fund /boot/grub2 that
> I've missed?
>
>  mark
>
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[m . roth]

Let me see if I can, um, reboot this thread

I made a RAID 1 of two raw disks, /dev/sda and /dev/sdb, *not* /dev/sdax
/dev/sdbx. Then I installed CentOS 7 on the RAID, with /boot, /, and swap
being partitions on the RAID. My problem is that grub2-install absolutely
and resolutely refuses to install on /dev/sda or /dev/sdb.

I've currently got it up in a half-assed rescue mode, and have mount -o
bind /dev, /proc/ and /sys under /mnt/sysimage, and chrooted there. That's
where I'm trying to do my grub2-install.

So:
  1. *Is* there space for grub2 to install the bootloader under where the
mdadm starts?
Or do I have to partition the disks (/dev/sda1 100%, ditto
/dev/sdb1, then
create the RAID 1 with the partitions, and *then* grub2-install?
  2. I *think* that one thing that grub2-install is complaining about is
that it can't
   find /boot/grub2. I've tried doing it with
$  grub2-install --boot-directory=/boot /dev/sda
   and
$  grub2-install --boot-directory=/dev/md127p1/ /dev/sda
   and
$  grub2-install --boot-directory=/dev/md127pw/boot /dev/sda
   and it tells me it cannot find the canonical path for the grub2
directory. Is
   there some way to specify where it should fund /boot/grub2 that
I've missed?

 mark

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[mark]

On 01/24/17 19:00, Gordon Messmer wrote:

On 01/24/2017 02:14 PM, m.r...@5-cent.us wrote:

So, it installed happily.
Then wouldn't boot.


What did the storage configuration look like, exactly?  I'd guess that you put
one partition on each disk, combined those in a RAID1 MD array, made than an
LVM physical volume, and then created filesystems and swap on LVs.  But that's
a lot of guesses.  Did you use MBR partitions or GPT?  Are you booting under
BIOS or UEFI?  Where do your partitions start?  Did you create a standard MD
RAID volume and LVM or a partitionable RAID volume and partitions?


No. Brand new machine, pulled it out of the box and racked it. NOTHING on the 
internal SSDs. Made an md RAID 0 on the raw disks - /dev/sda /dev/sdb. No 
partitions, nothing. However, when I bring it up, fdisk shows an MBR with no 
partitions. I can, however, mount /dev/md127p3 as /mnt/sysimage, and all is there.


Did I need to make a single partition, on each drive, and then make the RAID 1 
out of *those*? I don't think I need to have /boot not on a RAID.


mark

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Pete Biggs]

On Tue, 2017-01-24 at 17:14 -0500, m.r...@5-cent.us wrote:
> So, it installed happily.
> 
> Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
> grub2-install.
> 
> Um, nope. I edited the device map from hd0 and hd1 being the RAID to
> /dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
> identify the filesystem on hd0, and can't perform a safety check, and
> gives up.
> 
> What am I missing? Google is not giving me any answers
> 

Surely, if you are using software RAID, then you should configure that
RAID in anaconda, that will then cope with setting up the partitions to
allow booting.  Basically it needs a small non-RAID partition to hold
/boot on the boot disk.

Remember that the boot sequence is generally: BIOS reads MBR and
executes it; MBR code reads kernel from /boot and executes it (yes,
it's more complicated than that). If the MBR code doesn't know how to
read a RAID partition, then it's going to fail, that's why you have a
small non-RAID partition to hold /boot.

Hardware RAID is different because it interfaces at the BIOS level so
the MBR code doesn't need to know how to specifically read it.

P.
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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[Valeri Galtsev]

On Tue, January 24, 2017 4:14 pm, m.r...@5-cent.us wrote:
> So, it installed happily.
>
> Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
> grub2-install.
>
> Um, nope. I edited the device map from hd0 and hd1 being the RAID to
> /dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
> identify the filesystem on hd0, and can't perform a safety check, and
> gives up.

This is an interesting logical contradiction (unless things progressed
much farther than what I last read):

If you want to boot off your RAID1 device you need software RAID piece of
code already running, i.e. kernel already loaded, to load which which in
the first place you needed md0 or whichever device to exist to load it
from...

The only way around that I remember people were using was: cutting small
partition off the drive to keep it as a regular partition, and have /boot
on it. The rest of the drive can be different partition which can
participate in software RAID. For mirror (RAID-1) I remember people were
cutting the same piece off the beginning of both drives, one is always
active /boot (another can be maintained as a copy of it, but if you loose
first drive, you will need to install grub bootsector to second drive
pointing to /boot copy on that drive for loading initramdrive).

Anyway, good luck. Getting hardware RAID controller will be waaay less
hassle at all stages of your machine's life.

Valeri

>
> What am I missing? Google is not giving me any answers
>
>   mark
>
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] CentOS 7 install on one RAID 1 [not-so-SOLVED]

[m . roth]

So, it installed happily.

Then wouldn't boot. No problem, I'll bring it up with pxe, then chroot and
grub2-install.

Um, nope. I edited the device map from hd0 and hd1 being the RAID to
/dev/sda and /dev/sdb, then ran grup2-install. It now tells me can't
identify the filesystem on hd0, and can't perform a safety check, and
gives up.

What am I missing? Google is not giving me any answers

  mark

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Re: [CentOS] CentOS 7 install on one RAID 1 [SOLVED]

[Valeri Galtsev]

On Tue, January 24, 2017 1:10 pm, m.r...@5-cent.us wrote:
> Gordon Messmer wrote:
>> On 01/24/2017 08:33 AM, m.r...@5-cent.us wrote:
>>> I'm building a new box, and I want three partitions - /boot, /, and
>>> swap, on*one*  RAID 1, not three separate partitions. Other than
>>>  mdadm...,*is*  there any way in the graphical installer to do
>>> this? All I see is a way to make three separate partitions.
>>
> If that wasn't clear, I meant to make the two drives into a single RAID 1,
> *then* partition that for root, swap, and boot.
>>
>> I don't know the answer to that question, but what I can tell you is
>> that I handle software RAID setup in kickstart, creating the partitions
>> manually, so that I can replace drives using a shell script.  Making the
> 
> Trouble is, it's for this one box. Next box, or the one after, will be
> happy with the kickstart as it is.
>
> The solved part: I did the  and created the RAID 1.

The trouble is: this will be not part of your /root/initial-setup-ks.cfg
file after installation completes. That means, you will have to do that
part (which basically makes drives members of software RAID - mirror)
before kickstart installation on each box. Or you may need to add this
part at the very top of your kickstart file, followed by something like

 mdadm --assemble --scan

- I'm not certain though to what extent it is doable. I'm a "hardware
RAID" guy...

Valeri

> I went back to
> the GUI, and tried to rescan... it didn't find it, didn't show any drives,
> then it showed the two real drives... then it gagged, and crashed, and
> rebooted. HOWEVER, when I tried the next time, anaconda's probing found
> the RAID, and I'm installing now.
>
> *phew*
>
>  mark
>
>
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] CentOS 7 install on one RAID 1 [SOLVED]

[m . roth]

Gordon Messmer wrote:
> On 01/24/2017 08:33 AM, m.r...@5-cent.us wrote:
>> I'm building a new box, and I want three partitions - /boot, /, and
>> swap, on*one*  RAID 1, not three separate partitions. Other than
>>  mdadm...,*is*  there any way in the graphical installer to do
>> this? All I see is a way to make three separate partitions.
>
If that wasn't clear, I meant to make the two drives into a single RAID 1,
*then* partition that for root, swap, and boot.
>
> I don't know the answer to that question, but what I can tell you is
> that I handle software RAID setup in kickstart, creating the partitions
> manually, so that I can replace drives using a shell script.  Making the

Trouble is, it's for this one box. Next box, or the one after, will be
happy with the kickstart as it is.

The solved part: I did the  and created the RAID 1. I went back to
the GUI, and tried to rescan... it didn't find it, didn't show any drives,
then it showed the two real drives... then it gagged, and crashed, and
rebooted. HOWEVER, when I tried the next time, anaconda's probing found
the RAID, and I'm installing now.

*phew*

 mark


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Re: [CentOS] CentOS 7 install on one RAID 1

[Gordon Messmer]

On 01/24/2017 08:33 AM, m.r...@5-cent.us wrote:

I'm building a new box, and I want three partitions - /boot, /, and
swap, on*one*  RAID 1, not three separate partitions. Other than
 mdadm...,*is*  there any way in the graphical installer to do
this? All I see is a way to make three separate partitions.



I don't know the answer to that question, but what I can tell you is 
that I handle software RAID setup in kickstart, creating the partitions 
manually, so that I can replace drives using a shell script.  Making the 
partitions predictable means there's less of a chance that I'll make 
errors during drive replacement, and that I can pass that duty on to 
less experienced co-workers without worrying about it.


https://bitbucket.org/gordonmessmer/kickstart/src


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Re: [CentOS] CentOS 7 install on one RAID 1

[Leon Fauster]

> Am 24.01.2017 um 17:33 schrieb m.r...@5-cent.us:
> I'm building a new box, and I want three partitions - /boot, /, and swap, on 
> *one* RAID 1, not three separate partitions.


the first sentence is in conflict with the last one ("I want three partitions" 
vs. "not three separate partitions")


> Other than  mdadm..., *is* there any way in the graphical installer 
> to do this? All I see is a way to make three separate partitions.
> 
>   Pointers to links happily accepted.

A hardware RAID will provide one device that can be partitioned or use LVM on 
one MD RAID (software version).

--
LF


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