howto: restore to new disk

2005-09-09

Recently the firewall box' hard drive developed a squeal. Not good, especially when it changes note! This brief howto describes restoring a working system to a new hard drive with a clean install of Slackware-current (10.2 beta).

contents

what

The risk with high uptime boxen is that the hard drive may fail to spin up after a power cycle. When the hard drive bearing started squealing after 14 months operation, I decided it would be a good idea to replace the drive prior to failure.

The box deltree is an old pentium 233/mmx with 96MB memory. Could it handle an 80GB drive? Checked that by borrowing a 40GB HDD from another box. Not a problem, go buy a new 80GB drive and plan the replacement.

preparation

plan drive layout

old drive layout

I'm writing this after the event, the old hard drive is mounted in a different machine as /dev/hdb. 

# fdisk -l /dev/hdb

Disk /dev/hdb: 3243 MB, 3243663360 bytes
128 heads, 63 sectors/track, 785 cylinders
Units = cylinders of 8064 * 512 = 4128768 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdb1               1           4       16096+  83  Linux
/dev/hdb2               5          28       96768   82  Linux swap
/dev/hdb3              29         192      661248   83  Linux
/dev/hdb4             193         785     2390976    5  Extended
/dev/hdb5             193         232      161248+  83  Linux
/dev/hdb6             233         248       64480+  83  Linux
/dev/hdb7             249         256       32224+  83  Linux
/dev/hdb8             257         768     2064352+  83  Linux
/dev/hdb9             769         784       64480+  83  Linux

# df
Filesystem           1K-blocks      Used Available Use% Mounted on
[...]
/dev/hdb3               661220    339916    321304  52% /mnt
/dev/hdb5               156155     25343    122750  18% /mnt/var
/dev/hdb6                62437       154     59059   1% /mnt/usr/local
/dev/hdb8              2064252    894100   1170152  44% /mnt/home
/dev/hdb9                62437         2     59211   1% /mnt/home/ftp/upload

new drive layout

Basically the same layout with a little more elbow room and a pair of 32GB archive partitions. This box has been in use for 14 months and the requirements are known and settled. Make all partitions reiserfs, put entire ftp directory into its own partition and add a couple of large partitions, one for install source, the other an archive at the slow end of the drive, not normally mounted. 

# fdisk -l

Disk /dev/hda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hda1               1           4       32098+   6  FAT16
/dev/hda2   *           5         260     2056320   83  Linux
/dev/hda3             261         292      257040   82  Linux swap
/dev/hda4             293        9728    75794670    5  Extended
/dev/hda5             293         324      257008+  83  Linux
/dev/hda6             325         356      257008+  83  Linux
/dev/hda7             357         388      257008+  83  Linux
/dev/hda8             389        1412     8225248+  83  Linux
/dev/hda9            1413        5508    32901088+  83  Linux
/dev/hda10           5509        9728    33897118+  83  Linux

# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/hda2              2056252    478928   1577324  24% /
/dev/hda5               256996     41852    215144  17% /var
/dev/hda6               256948     32928    224020  13% /usr/local
/dev/hda8              8224960    495892   7729068   7% /home
/dev/hda7               256948     33080    223868  13% /home/ftp
/dev/hda9             32900044   5520728  27379316  17% /home/install
/dev/hda10            33896048   1362304  32533744   5% /home/archive
Constraints
The drive may have up to four primary partitions, one of which may be labelled extended that may contain logical partitions. Maximum number of partitions is 16, some systems allow more, some ignore partitions greater than 16.
Sizing
Experience helps here, as sizing depends on many factors, when in doubt, leave some unallocated space for later.
Layout
I plan new layout on paper, so the plan for the new layout above looks something like: 

 1	 32MB	   4	spare
 2	  2GB	 256	/
 3	256MB	  32	swap
 4	  -		ext
 5	256MB	  32	/var
 6	256MB	  32	/usr/local
 7	256MB	  32	/home/ftp
 8	  8GB	1024	/home
 9	 32GB	4096	/home/install
10	 32GB	 -	/home/archive
The number in the third column above is the cylinder count, a multiple of eight gives integer 4k partition sizes.
Place the busiest partitions near front of drive, for example the Seagate drive I use has a 2:1 data rate difference from outer to inner edge of the disk (58 - 28 MB/s). Also think of head movement, that's why I clustered the small partitions together.
The small dos primary is so I may later add cdrom and other boot options via dos as box cannot boot cdrom.

fdisk + reboot

I prefer fdisk, but you should use tools that you feel comfortable with. It is vital you reboot after writing out a new partition table, prior to formatting the new partitions.

format

You may prefer to defer formatting to the install phase, I needed to format drive in order to copy install source, so I formatted the whole thing. I choose Reiserfs-3 as it has not let me down. Choose the filesystems you prefer.

copy install source

Skip this if you prefer a CD or NFS install, I find a hard drive install convenient as it sidesteps the issue of which of the three NICs will the slack installer see first?

make boot floppies

Skip this. Unless you cannot boot CDROM. Write and verify the three boot floppies, this is covered in the Slackware documentation.

halt + swap drives

Ready to install. Shutdown the box and swap hard drives. While one may argue that the install be done on another box, this is part of acceptance testing for the new hard drive in its intended role.

installation

Install Slackware as per the rich documentation elsewhere.

restore procedure

In this section we restore the box' personality, user data files, to the fresh Slackware system to bring back the firewall function.

backups

Normal backups for this system are one tarball for the OS with kernel configs, /etc, usr/local; and another for the web data area. OS is reinstalled, install area is local copy of files available from the Internet thus no need to backup. In choosing what to backup consider cost of replacing missing data: download time, creation time, backup capacity and convenience.

localnet controller

Mount old HDD partitions and use rsync to take an archive copy remove old hard drive. Edit/merge system config files:

Copy system config files from backup:

(Optional) Compile or reinstall custom kernel, this box' kernel is compiled on another box, once NFS is working install custom kernel, reboot.

Restore localnet file server data, in this case rsync copy the /home/share tree from backup. Check for correct localnet operation.

ADSL

Time to reinstate world access, copy config files from backup:

Run adsl-start and verify ADSL connection, firewall and world access.

servers

apache
restore /etc/apache/httpd.conf, rsync copy /home/web from archive, `apachectl graceful`
ftp
restore /etc/vsftpd.conf, rsync /home/ftp from backup, restart vsftpd
samba
restore /etc/samba/smb.conf, restart samba
ntp
restore /etc/ntp.conf, ntpdate <server>, kick ntpd
FIXME 
repeat
  dd copy boot_image to floppy
  verify floppy
until floppy == image

commands:
	dd if=/path/to/bootdisk/bare.i of=/dev/fd0
	cmp /path/to/bootdisk/bare.i /dev/fd0


quite painless really.

gotchas

references