Expanding RAID5 guidance - SOLUTION/RESULTS
Jeff Boyce
jboyce at meridianenv.com
Mon Mar 2 13:40:58 CST 2009
See posting at bottom.
----- Original Message -----
From: "Jeff Boyce" <jboyce at meridianenv.com>
To: <linux-poweredge at dell.com>
Sent: Friday, January 30, 2009 2:33 PM
Subject: Expanding RAID5 guidance
> Greetings -
>
> I am a novice Linux user that manages a file server for a small business
> and am looking for a little general guidance on understanding the right
> steps for expanding the storage capacity on a Dell Server. Sorry for the
> long post, but I know how irritating it is when people don't describe
> their objective or provide all the details for someone else to understand
> the problem.
>
> Existing Server Setup:
> Dell PE 2600
> PERC 4/Di
> 3 - 36GB hard drives in Raid5
> 1 - 36GB dedicated hot spare
> No LVM used
> RHEL 3 update 9
> OMSA 5.1
> Used as small office Samba file server
>
> Proposed Objective:
> Add 2 - 36GB drives in remaining spare slots
> Expand Raid5 to include the added space
> Make use of the added space by users of the file server
>
> I know the first rule of thumb with managing raids and file systems is to
> have good backups (multiple backups are better) and I am writing up a
> detailed list of additional files to backup besides my home and data
> directories, so I think I have this covered. My second task has been to
> make sure that I have a rescue disk or reinstallation disks available in
> case its needed. If OS installation becomes necessary for some reason I
> am considering upgrading to 5.2 (but that is beside the point).
>
> I have read through the OMSA user guide and feel comfortable going through
> the task to physically install the new drives, and the steps for
> reconfiguring the existing virtual disk. This point is were my
> information and comfort level begins to fall apart. The first questions
> that I would like answered is:
>
> 1. How long does the reconfiguration process take (I will do this on a
> weekend when no one is using the system)?
> 2. How do I know when the reconfiguration process is done (something the
> user guide doesn't describe)? As you can see I want to know what to
> expect (good or bad) prior to completing the reconfiguration.
>
> Then from my reading of numerous descriptions of expanding raids through
> google searches (including a decent summary of the steps written by Matt
> Domsch (Expanding Storage on Linux-based Servers, Feb. 2003) it appears
> that I will need to expand the file system to use the new space; but do I
> also need to add/create a new partition for this space, or can I expand an
> existing partition into this space. What I would like to do is just
> expand one or two existing partitions and distribute this space among
> them, if that is possible (see fstab listed below). So my next questions
> would be:
>
> 3. What are the general steps that I need to do after my raid
> reconfiguration is complete to achieve my general objective?
> 4. Would it be possible to add the new space to one or two existing
> partitions? I am thinking sda2 and sda10 (/ecosystem is our samba share
> data directory that would be given 90% of the new space).
> 5. Will I need to add/create a new partition (and samba mount point) to
> make use of the new space? If so I could reorganize our data files to
> make use of two samba mount points.
> 6. Any other pitfalls I should be aware of, such as what steps need to be
> done on unmounted drives?
>
> Thanks for any and all comments and suggestions; good howto links are
> always welcome.
>
> FSTAB
> -------------------------
> LABEL=/ / ext3 defaults 1
> 1
> LABEL=/boot /boot ext2 defaults 1
> 2
> none /dev/pts devpts gid=5,mode=620 0
> 0
> none /proc proc defaults 0
> 0
> none /dev/shm tmpfs defaults 0
> 0
> LABEL=/tmp /tmp ext3 defaults 1
> 2
> LABEL=/usr /usr ext3 defaults 1
> 2
> LABEL=/var /var ext3 defaults 1
> 2
> /dev/sda9 swap swap defaults 0
> 0
> /dev/sda2 /home ext3 defaults 1 2
> /dev/cdrom /mnt/cdrom udf,iso9660
> noauto,owner,kudzu,ro 0 0
> /dev/fd0 /mnt/floppy auto noauto,owner,kudzu
> 0 0
> /dev/st0 /mnt/tape ext3 noauto,owner,kudzu 0 0
> /dev/sda10 /ecosystem ext3 defaults 1 2
>
> RECENT LOGWATCH OUTPUT
> ------------------ Disk Space --------------------
> Filesystem Size Used Avail Use% Mounted on
> /dev/sda7 2.0G 1.5G 385M 80% /
> /dev/sda3 190M 54M 128M 30% /boot
> none 501M 0 501M 0% /dev/shm
> /dev/sda8 1012M 33M 928M 4% /tmp
> /dev/sda5 9.7G 2.8G 6.4G 31% /usr
> /dev/sda6 9.7G 2.9G 6.3G 32% /var
> /dev/sda2 2.5G 2.0G 443M 82% /home
> /dev/sda10 40G 35G 3.7G 91% /ecosystem
>
>
> Jeff Boyce
> www.meridianenv.com
I finally had my scheduled maintenance down time and completed this task. I
thought I would share generally what I did and how I did it in case there
are other novice administrators out there interested.
1. Ran my normal tape backup on the Friday night before the down weekend to
backup all data files.
2. Rebooted the system to verify it shuts down and restarts properly.
System had been up 450+ days so this initiated a file system check which was
also my plan.
3. Modified my /etc/fstab so that I could mount a usb flash drive and a usb
connected portable hard drive.
4. Copied some specific rpm's and system files to the flash drive.
5. Installed GParted LiveCD and rebooted so that the drives were not
mounted.
6. Made an image of the server onto the usb connected portable hard drive.
In case something goes very wrong in subsequent steps.
# dd if=/dev/sda of=/dev/sdb bs=8192 conv=noerror,sync
This does not give any progress report to indicate how long it would
take so I opened another terminal and ran the following command to force the
dd command to give me a periodic status report.
# watch -n120 -- pkill -USR1 ^dd$
Since the usb transfer rate was 1.1 MB/sec it took about 18 hours to
transfer about 70 GB.
7. Unmounted the usb portable drive, shut down GParted, and powered down
the server.
8. Vacuumed all the dust from the server and installed the two new hard
drives in my last open slots.
9. Rebooted the system in the standard OS in order to use OMSA tools.
10. In OMSA selected the Virtual Disk, chose the reconfigure task, and
selected execute to step through the steps to select the new physical disks
to include in the virtual disk, the raid type, and the size for the
reconfigured virtual disk.
11. OMSA gives a progress report during the reconfiguration process. It
took about 1 hour and 10 minutes to complete reconfiguring a 3 disk raid 5
of 67GB to a 5 disk raid 5 of 135GB.
12. Reboot the server using the GParted LiveCD so that the drives were not
mounted.
13. My goal was to just expand my existing last partition (sda10) into the
new space. However I realized that I had to expand my existing "extended
partition" (sda4) first to include the new space, then expand the last
partition (sda10) and grow the filesystem into the space.
14. Remove the GParted LiveCD and rebooted to the standard OS.
15. Checked OMSA Virtual Disk and it indicated that it was conducting a
background initialization, which took about 1 hour to complete.
16. Checked the new size of the Samba share (sda10) on a Windows client box
and everything looked good.
When I returned to the office on Monday morning the staff was working on the
Samba share without even noticing anything had changed. I am glad no one
noticed the change. Success goes unnoticed by normal users, failure gets
noticed. I would like to thank everyone that educated me and gave me
guidance (both on- an off-list) on how to complete this task and what to
expect. And I hope now that some other novice might learn from my
description.
Jeff Boyce
www.meridianenv.com
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