[CentOS] Un Installing a hard drive in a Centos 5.1 box

Pam Astor pamastor at hotmail.com
Thu Mar 20 20:46:52 UTC 2008


>>>>>I'm fairly new to Linux and I'm trying to un install a hard drive from my Centos 5.1
>>>>>box running KDE. When I built the PC, I installed two 500 gig maxtors in the tower,
>>>>>then I installed Centos. Now I've decided that I want to remove the slave drive and
>>>>>use it as an external backup drive - I am mounting it into one of those external
>>>>drive cases with a built in fan.
>>>>>
>>>>>When I physically removed the drive and restarted the PC, centos would not boot up and
>>>>>went into a kernel panic. I'm sure I'm supposed to somehow unmount the thing before
>>>>>I do this, and that's my question - how do I un-install the hard drive - software
>>>>>wise - so that on next boot up, centos don't go crazy looking for it?
>>>>
>>>>run
>>>># mount
>>>>this will show the mounted partitions. find the partitions that are on
>>>>the second drive and unmount them:
>>>># umount /path/to/partition
>>>>if a service uses them, you'll see an error. you will need to fix the
>>>>errors until you can unmount them.
>>>>then comment out these partitions in /etc/fstab.
>>>
>>>OK this is what I have when I run mount - does it appear that
>>>I have both drives on one volume?:
>>>
>>>
>>> /dev/mapper/VolGroup00-LogVol00 on /
>>>type ext3 (rw)
>>>proc on /proc type proc (rw)
>>>sysfs on /sys type sysfs (rw)
>>>devpts on /dev/pts type devpts
>>>(rw,gid=5,mode=620)
>>>/dev/sda1 on /boot type ext3 (rw)
>>>tmpfs on /dev/shm type tmpfs (rw)
>>>none on /proc/sys/fs/binfmt_misc type
>>>binfmt_misc (rw)
>>>sunrpc on /var/lib/nfs/rpc_pipefs type
>>>rpc_pipefs (rw)
>>
>>If the machine panics at boot time, there is a good chance that you
>>installed with LVM and its got both the drives into one volume. You will
>>need to reinstall that second harddrive, then work out the process of
>>shrinking the filesystem down to only 1 drive, then remove the second
>>drive. The scope of this work might be too much for an email, so I can
>>best point you at the LVM HowTo. There are also some good lvm tips in
>>the CentOS5 docs ( http://www.centos.org/docs/5/ )
>>
>
>am Astor wrote:
>> OK this is what I have when I run mount - does it appear that
>> I have both drives on one volume?:
>>
>> /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw)
>>
>>
>>what output to do you get from :
>>pvdisplay; vgdisplay; lvdisplay

>[root at localhost ~]# pvdisplay; vgdisplay; lvdisplay
> --- Physical volume ---
> PV Name /dev/sdb1
> VG Name VolGroup00
> PV Size 465.76 GB / not usable 9.50 MB
> Allocatable yes (but full)
> PE Size (KByte) 32768
> Total PE 14904
> Free PE 0
> Allocated PE 14904
> PV UUID IAmE1f-dCMo-c035-cSQQ-g9yE-6yOo-mfKhHv
>
> --- Physical volume ---
> PV Name /dev/sda2
> VG Name VolGroup00
> PV Size 465.66 GB / not usable 3.56 MB
> Allocatable yes (but full)
> PE Size (KByte) 32768
> Total PE 14901
> Free PE 0
> Allocated PE 14901
> PV UUID fi5A7U-dao0-ruuP-TSc0-LfFu-7yRL-iKnwGr
>
> --- Volume group ---
> VG Name VolGroup00
> System ID
> Format lvm2
> Metadata Areas 2
> Metadata Sequence No 3
> VG Access read/write
> VG Status resizable
> MAX LV 0
> Cur LV 2
> Open LV 2
> Max PV 0
> Cur PV 2
> Act PV 2
> VG Size 931.41 GB
> PE Size 32.00 MB
> Total PE 29805
> Alloc PE / Size 29805 / 931.41 GB
> Free PE / Size 0 / 0
> VG UUID pwO7bQ-0eRs-W8O4-b4uf-hYe6-JIm6-27p8wu
>
> --- Logical volume ---
> LV Name /dev/VolGroup00/LogVol00
> VG Name VolGroup00
> LV UUID avhFcY-30N6-2BPz-A89X-Ai0V-v5B7-xxzhIe
> LV Write Access read/write
> LV Status available
> # open 1
> LV Size 929.47 GB
> Current LE 29743
> Segments 2
> Allocation inherit
> Read ahead sectors 0
> Block device 253:0
>
> --- Logical volume ---
> LV Name /dev/VolGroup00/LogVol01
> VG Name VolGroup00
> LV UUID ZW2z5f-5x58-0vDI-ru5S-iZge-mVE6-yVp160
> LV Write Access read/write
> LV Status available
> # open 1
> LV Size 1.94 GB
> Current LE 62
> Segments 1
> Allocation inherit
> Read ahead sectors 0
> Block device 253:1
>
>And...
>
>[root at localhost ~]# df -h
>Filesystem Size Used Avail Use% Mounted on
>/dev/mapper/VolGroup00-LogVol00
> 901G 6.7G 848G 1% /
>/dev/sda1 99M 18M 76M 20% /boot
>tmpfs 1.9G 0 1.9G 0% /dev/shm
>[root at localhost ~]#

>yup, its all 1 Volume, you are going to need to shrink the lv's - then
>get your volgroup onto /dev/sda only. info on howto do that is in the
l>vm howto. also, I'd recommend you download the centos-5.1/livecd and
>actually do the work once booted from the livecd. shinking filesystems
>requires you to have the filesystem unmounted, so doing it from the
>livecd is the only way you are going to manage it here.

OK when you say livecd, do you mean the Centos 5.1 distro
disks? I have a full set of them, a 7 disk set I got from Linux Central.
Can I just boot off disk 1 from my set?

...or, if I left the install the way it is now, are there any dis advantages of leaving the file
system the way it is - spread over two hard drives?
Should just get another hard drive and back it up the way it is?
Would ther be any problems with my backup if left the way it is?

Or ahould I just do a complete re install of the OS after backing up my data...

What do you reccomend -leave it as is, re configure it, or re install it?

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