Clone local drive with rsync?? Advice needed

[CaMer0n]

Can anyone explain how I might go about backing up an entire (server/drive) to another one in the same machine - at regular intervals? (ie. cron)

Basically, the main hard-drive in the system has been a little unreliable lately, and I'd like to clone it (ie. WITHOUT compression/tars etc) so in the event of a failure, the 2nd drive could be swapped over and everything would run as usual.

Here's the physical drives of the system:
hda: WDC WD2500JB-75FUA0, ATA DISK drive
hdb: ST3250820A, ATA DISK drive
hdc: SAMSUNG CD-ROM SC-148A, ATAPI CD/DVD-ROM drive
hda: max request size: 1024KiB
hda: 488281250 sectors (250000 MB) w/8192KiB Cache, CHS=30394/255/63, UDMA(100)
hda: cache flushes supported
hdb: max request size: 1024KiB
hdb: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63, UDMA(100)
hdb: cache flushes supported
hdc: ATAPI 48X CD-ROM drive, 128kB Cache, UDMA(33)


hda contains everything.

/dev/hda5 7.9G 385M 7.1G 6% /
/dev/hda1 122M 33M 83M 29% /boot
none 506M 0 506M 0% /dev/shm
/dev/hda6 189G 88G 92G 49% /home
/dev/hda7 1012M 319M 642M 34% /tmp
/dev/hda2 20G 4.0G 15G 22% /usr
/dev/hda3 9.9G 424M 9.0G 5% /var
/tmp 1012M 319M 642M 34% /var/tmp

And I'd like to copy everything (partitions, files, boot record etc) to hdb which has just been added by the datacenter.

So, can rsync do this? and If so, with what command?

Sorry for all the questions, but after researching on the web, and in this forum, I haven't found a clear answer.. but I have learned that done incorrectly, I could seriously mess up the existing data.

Thanks in advance.

[troxalias]

*** I TAKE NO RESPONSIBILITY FOR THE INSTRUCTIONS BELOW ***
As i don't feel very comfortable with rsync, i would use a "dump'n'restore" approach. So...
1. Copy the mbr and partition table from hda to hdb with the command

dd if=/dev/hda of=/dev/hdb count=16

2. create a dummy chroot dir with the commands

mkdir -p /home/SECONDDRIVE/boot
mkdir /home/SECONDDRIVE/home
mkdir /home/SECONDDRIVE/usr
mkdir /home/SECONDDRIVE/var

3. create file system on the new drive

newfs /dev/hdb1
newfs /dev/hdb2
newfs /dev/hdb3
newfs /dev/hdb5
newfs /dev/hdb6
newfs /dev/hdb7

4. Mount the new partitions to the appropriate folders with the command:

mount /dev/hdb5 /home/SECONDDRIVE/
mount /dev/hdb1 /home/SECONDDRIVE/boot
mount /dev/hdb2 /home/SECONDDRIVE/usr
mount /dev/hdb3 /home/SECONDDRIVE/var
mount /dev/hdb6 /home/SECONDDRIVE/home

5. Dump and restore data on the new drive with the commands:

dump cf - / | (cd /home/SECONDDRIVE/; restore xf - )
dump cf - /boot | (cd /home/SECONDDRIVE/boot; restore xf - )
dump cf - /usr | (cd /home/SECONDDRIVE/usr; restore xf - )
dump cf - /var | (cd /home/SECONDDRIVE/var; restore xf - )
dump cf - /home | (cd /home/SECONDDRIVE/home; restore xf - )

[chirpy]

Bear in mind that this would likely generate corrupt MySQL databases if you have them stored on the drive. These need to be dumped to text files beforehand and then restored from the dumps.

[CoolMike]

Is there any other solution to replicated a disc during the main disk is in normal operation? This would be a very good solution to make backups, in case a disk is broken, you just replace the disk and everything is running again. No need for OS reload, WHM installation and Cpanel Backup restore.

Or is the replication to disk I/O intensive?

Michael

[CaMer0n]

thanks troxalias,

I got to step 3, and get '-bash: newfs: command not found
'.

Was I meant to substitute "seconddrive" with something in step2?

Thanks.. and sorry for the noob questions.

Cameron

[tomdchi]

Is there any other solution to replicated a disc during the main disk is in normal operation? This would be a very good solution to make backups, in case a disk is broken, you just replace the disk and everything is running again. No need for OS reload, WHM installation and Cpanel Backup restore.

Or is the replication to disk I/O intensive?

Michael

How about using RAID? I have never used before but am about to with new server.

[chirpy]

RAID isn't a reliable method for duplicating data for this purpose and doesn't address the issue of MySQL database corruption. To avoid that, you're better off using a backup MySQL database that will duplicate transactions in realtime. Setting that up is straightforward.

[CaMer0n]

chirpy, what would you recommend for cloning/mirroring a drive?

rsync, dd or maybe some other software?

thanks

[chirpy]

If you want remote synchronisation, then rsync would probably by the best way with periodic updates from the liver server. Together with a duplicate MySQL server to keep that up to date.

[devGOD]

If you want remote synchronisation, then rsync would probably by the best way with periodic updates from the liver server. Together with a duplicate MySQL server to keep that up to date.

can you post a how-to, showing how you would do the mirroring of another drive