CentOS - Mar 2005 - raid mirroring on existing CentOS 4 installation?

Greetings

I have a simple Intel 865PERL motherboard and 1.8GHz processor test server
w/ CentOS 4 on it. It was upgraded from 3.3 to 3.4 then "linux
upgradeany"
to 4.0.

Ok, I started with one 40G PATA WD hard drive (/dev/hda) and just added a
second identical drive on the slave controller and it is (/dev/hdc)

I think /dev/hdb is the DVD/CDROM

Here is the first drive /dev/hda on my test box.

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/hda1              1004024    361112    591908  38% /
/dev/hda6              5036284     35016   4745436   1% /home
/dev/hda7              5036284     34920   4745532   1% /home/vpopmail
none                    517520         0    517520   0% /dev/shm
/dev/hda5              5218040     32924   4920048   1% /tmp
/dev/hda2             10080520   4143052   5425400  44% /usr
/dev/hda3             10080520    280508   9287944   3% /var

Disk /dev/hda: 40.0 GB, 40020664320 bytes
255 heads, 63 sectors/track, 4865 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1   *           1         127     1020096   83  Linux
/dev/hda2             128        1402    10241437+  83  Linux
/dev/hda3            1403        2677    10241437+  83  Linux
/dev/hda4            2678        4865    17575110    f  W95 Ext''d (LBA)
/dev/hda5            2678        3337     5301418+  83  Linux
/dev/hda6            3338        3974     5116671   83  Linux
/dev/hda7            3975        4611     5116671   83  Linux
/dev/hda8            4612        4865     2040223+  82  Linux swap

Ok, so... can I upgrade to mirroring on the fly? Is there a specific URL I
should be learning from on this?

When I get tired of this playpen and go to a fresh "test" install,
what
mirroring install facts and knowledge should I be following at that time
please?

In the very near future, I want to go to a large spin fast read/write hot
swap RAID architecture. Sooooooooooo...

Do you folks have any recommendations as to what URL''s I should be
looking
at in the future for going to my long term goal of SATA RAID5 with an
aftermarket controller like 3ware or other CentOS happy hardware RAID
controllers?

Thank you in advance for your time.

 - rh

Before you buy anything, be aware of the fact that CentOS4 does not have
"built-in" support for either 3ware or adaptec SATA RAID cards, In
fact, it
doesn''t support many raid cards, at all.

Your best best will be the LSI or MegaRaid cards.

Also, if you read the digest version of this list, since the beginning of the
month, there were quite a number of posts regarding Raid and CentOS4,
including a few from me.

Good Luck.

Michael Weisman
The Ad Doctors
mike@theaddoctors.com

On Monday 21 March 2005 17:03, Robert Hanson wrote:
> Greetings
>
> I have a simple Intel 865PERL motherboard and 1.8GHz processor test server
> w/ CentOS 4 on it. It was upgraded from 3.3 to 3.4 then "linux
upgradeany"
> to 4.0.
>
> Ok, I started with one 40G PATA WD hard drive (/dev/hda) and just added a
> second identical drive on the slave controller and it is (/dev/hdc)
>
> I think /dev/hdb is the DVD/CDROM
>
> Here is the first drive /dev/hda on my test box.
>
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/hda1              1004024    361112    591908  38% /
> /dev/hda6              5036284     35016   4745436   1% /home
> /dev/hda7              5036284     34920   4745532   1% /home/vpopmail
> none                    517520         0    517520   0% /dev/shm
> /dev/hda5              5218040     32924   4920048   1% /tmp
> /dev/hda2             10080520   4143052   5425400  44% /usr
> /dev/hda3             10080520    280508   9287944   3% /var
>
> Disk /dev/hda: 40.0 GB, 40020664320 bytes
> 255 heads, 63 sectors/track, 4865 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
>    Device Boot      Start         End      Blocks   Id  System
> /dev/hda1   *           1         127     1020096   83  Linux
> /dev/hda2             128        1402    10241437+  83  Linux
> /dev/hda3            1403        2677    10241437+  83  Linux
> /dev/hda4            2678        4865    17575110    f  W95 Ext''d
(LBA)
> /dev/hda5            2678        3337     5301418+  83  Linux
> /dev/hda6            3338        3974     5116671   83  Linux
> /dev/hda7            3975        4611     5116671   83  Linux
> /dev/hda8            4612        4865     2040223+  82  Linux swap
>
> Ok, so... can I upgrade to mirroring on the fly? Is there a specific URL I
> should be learning from on this?
>
> When I get tired of this playpen and go to a fresh "test"
install, what
> mirroring install facts and knowledge should I be following at that time
> please?
>
> In the very near future, I want to go to a large spin fast read/write hot
> swap RAID architecture. Sooooooooooo...
>
> Do you folks have any recommendations as to what URL''s I should be
looking
> at in the future for going to my long term goal of SATA RAID5 with an
> aftermarket controller like 3ware or other CentOS happy hardware RAID
> controllers?
>
> Thank you in advance for your time.
>
>  - rh
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@caosity.org
> http://lists.caosity.org/mailman/listinfo/centos

On Mon, 2005-03-21 at 22:20, Michael Weisman wrote:
> Before you buy anything, be aware of the fact that CentOS4 does not have
> "built-in" support for either 3ware or adaptec SATA RAID cards,
In fact, it
> doesn''t support many raid cards, at all.
Do the 3w-9xxx and 3w-xxxx drivers not cover any of the SATA variants?
> Your best best will be the LSI or MegaRaid cards.
>
> Also, if you read the digest version of this list, since the beginning of
the
> month, there were quite a number of posts regarding Raid and CentOS4,
> including a few from me.
The Areca SATA RAID cards are not supported out of the box on CentOS
4.0, but I''m providing drivers built for the CentOS kernels, which seem
to work fine on the card I have here.

Matt
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> Before you buy anything, be aware of the fact that CentOS4 does not have
> "built-in" support for either 3ware or adaptec SATA RAID cards,
In fact, it
> doesn''t support many raid cards, at all.
>
> Your best best will be the LSI or MegaRaid cards.
>
> Also, if you read the digest version of this list, since the beginning of
the
> month, there were quite a number of posts regarding Raid and CentOS4,
> including a few from me.
the 3ware 9xxx cards are directly supported by centos4.  i have a box
running centos4 with sata drives on the 9500S-4LP with no extra drivers
required.

> Before you buy anything, be aware of the fact that CentOS4 does not
> have "built-in" support for either 3ware or adaptec SATA RAID
cards,
> In fact, it doesn''t support many raid cards, at all.
> Your best best will be the LSI or MegaRaid cards.
> Also, if you read the digest version of this list, since the beginning
> of the month, there were quite a number of posts regarding Raid and
> CentOS4, including a few from me.
There is a 3ware module(s):

  /lib/modules/`uname -r`/kernel/drivers/scsi/3w-xxxx.ko
  /lib/modules/`uname -r`/kernel/drivers/scsi/3w-9xxx.ko


Meanwhile...

I wrote up the following procedure to setup LVM/mdadm RAID1 migrating
from a single disk to 2 NEW identical drives to become the mirror - you
can probably just retag the original drive as "Linux auto detect" and
skip the copying/cpio everything to a 2nd staging drive if you''re
feeling brave - otherwise, current hdc will become hda and current hda
will become the mirrored hdc. This is cnp''d from HTML document -
plaintext formatting may vary. Have NOT tested this against 4.0 (works
in 3.x) :



It is assumed that system is booted off of /dev/hda where /dev/hdc is an
identical drive upon which a new boot disk will be constructed. In
addition; example layout :

Partition 	Filesystem 	Metadevice
/dev/hda1 	/boot 		/dev/md1
/dev/hda2 	/ 		/dev/md2
/dev/hda3 	swap 		/dev/md3
/dev/hda5 	/export/home 	/dev/md5

    * If you''re adding a new disk that has a set of filesystems (and
e2fs labels) on it, you will need to clear the partition table before
installing it into a system, as the LABEL=/filesystem model gets easily
confused; e2label can be used to just erase labels. Remember if you
erase the labels, change /etc/grub/grub.conf and /etc/fstab to use
partition names, or you won''t be able to reboot!

   1. Ensure the disks are of the same type/size; Note: identical disks
may have different geometry settings which must be resolved
          * sfdisk -sg /dev/hda; sfdisk -sg /dev/hdc
   2. Copy the partition table (and geometry) from current to new disk
          * sfdisk -d /dev/hda | sfdisk /dev/hdc
	or
          * sfdisk -d /dev/hda | sfdisk -C <cyl> -H <head> -S
<sec> /dev/hdc
   3. Set the partition label on the new mirror drive to "Linux raid
autodetect" :
          * sfdisk -c /dev/hdc 1 fd
          * sfdisk -c /dev/hdc 2 fd
          * sfdisk -c /dev/hdc 3 fd
          * sfdisk -c /dev/hdc 5 fd
   4. Construct the RAID1 metadisk devices on each partition :
          * mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/hdc1
missing
          * mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/hdc2
missing
          * mdadm --create /dev/md3 --level=1 --raid-devices=2 /dev/hdc3
missing
          * mdadm --create /dev/md5 --level=1 --raid-devices=2 /dev/hdc5
missing
   5. Construct filesystems on metadisk devices :
          * mkfs -t ext3 /dev/md1
          * mkfs -t ext3 /dev/md2
          * mkfs -t ext3 /dev/md5
          * mkswap /dev/md3
   6. Copy filesystems from original to new mirror drive :
          * mkdir /mnt/new
          * mount /dev/md2 /mnt/new
          * cd /; find . -xdev | cpio -pmd /mnt/new
          * mount /dev/md1 /mnt/new/boot
          * cd /boot; find . -xdev | cpio -pmd /mnt/new/boot
          * mount /dev/md5 /mnt/new/export/home
          * cd /export/home; find . -xdev | cpio -pmd /mnt/new/export/home
   7. Update /etc/fstab file on new drive (/mnt/new/etc/fstab); replace
all LABEL=/ tags with /dev/md#
   8. Construct new initrd image which preloads the raid1 kernel module
          * RH73/9 env startraid=1 mkinitrd -f --preload=raid1
/mnt/new/boot/initrd-`uname -r`.img `uname -r`
                o RHEL/CentOS: can leave off the env startraid=1 part
                o repeat for any other bootable kernels on the system
   9. Update grub.conf file on new disk; remove all (hdX,0) references
and set the kernel root= option to the appropriate /dev/md device
that''s
the root filesystem :

      default=0
      timeout=10
      splashimage=/grub/splash.xpm.gz
      title Red Hat Linux (2.4.20-28.7smp)
         kernel /vmlinuz-2.4.20-28.7smp ro root=/dev/md1
         initrd /initrd-2.4.20-28.7smp.img


   10. Unmount the new disk: umount /mnt/md3; umount /mnt/md0; umount
/mnt/md1
   11. Run GRUB to setup bootloader :
          root (hd1,0); setup (hd1)
   12. Shutdown system, make new disk primary and check if it boots
(verify all root disk filesystems are mounted on /dev/mdX devices)

If all goes well, setup 2nd mirror disk (can recycle old boot disk) :

   1. Reset partition table (types and layout) :
          * sfdisk -d /dev/hda | sfdisk /dev/hdc
   2. Add the new mirror devices; monitor through /proc/mdstat :
          * mdadm --add /dev/md0 /dev/hdc1
          * mdadm --add /dev/md1 /dev/hdc2
          * mdadm --add /dev/md2 /dev/hdc3
          * mdadm --add /dev/md3 /dev/hdc5
   3. Setup GRUB loader on 2nd drive (can do this once /boot on /dev/md0
is finished) :
          root (hd1,0); setup (hd1)

    * Once all the mirrors are finished syncing up, you should be able
to swap drives and have the system reboot. Should a disk fail, you will
likely still have to physically remove it from the system (esp if IDE),
but the other drive should be intact. Use the last procedure above to
setup and reattach new mirror disk.


-ericb