Complete Hard Disk Image on spare drive

[lpittman]

Howdy,

I have just purchased a new server with 2 drives and would like to setup the second drive to be an image of the first drive that is bootable.

I have done extensive searching and have come up with basically 1 solid solution and wanted to get the feedback from the community...

From what I can tell the norm is to use the 'dd' command ... ie:

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

I'd like to have the drive backed up each morning at a certain time ... so the mirror will need to be quick, but can take a little bit of time. During this time however services cannot become unavailable.

Thanks for any information ..

Luke

 

[dmoses]

Have you considered using RAID?

You could use a 2 disk RAID 1 setup, which would be very similar to what you want but with a few bonuses:

1) You would not have to stop/pause any operations in order to perform a complete backup.
2) In the case of a failure, the backup drive would stand in place of the failed one, with no downtime.
3) In case of a failure the backup is current and not aged since your last backup operation.

Ideally you would use a hardware controller as compared to software RAID (for performance and flexibility)

 

[lpittman]

Thanks for the reply.

I'd love to use RAID, but unfortunatly my DC doesn't offer any RAID solutions at all right now. = (

So, this is as close as I can get ... any info from anyone would be a great help.

Luke

 

[dmoses]

My provider does not offer any RAID controllers either. Blah

Software RAID is included in almost every Linux distribution, so it is an option.... although maybe not want you want.

 

[lpittman]

Yea software raid is not what I'm looking for ... I want something that just runs at a certain time each day.

I know someone out there has an answer...

 

[dmoses]

If you use the ‘dd’ command or choose some other live disk method (the disk is currently mounted), you will have to consider the implications of programs writing data to the disk during your backup operation. If this is not considered your backup image may not be in a consistent state.

As an example, lets consider a MySQL database writing multiple records/tables to disk while you are backing up. If you are not using transactions, then your snap shot may be of the database in between updating multiple tables and therefore not in a consistent state. In this example there is an easy solution, you would want to lock and flush the tables before backing up, then release them afterwards. But that is at the cost of having the database unavailable while being backed up.

Even commercial solutions I looked at before do not handle such situations as above.

Anyways, just something to consider, I’ll let someone else reply now

 

[lpittman]

Thanks for the info ... yes I did consider that.

Currently I dump MySQL and rsync my entire server to a remote server .. this works fine, except it would be a pain in the butt to recover if anything major happened. I've never had any problems with stuff being written as rsync does its work. Rsync simply has a message at the end of the process saying "some files changed during process and did not upload" or whatever...

Can rsync work with the MBR and other boot information?

Luke

 

[faris]

Isn't there something like Ghost for Linux? This would almost do the trick. If it works the way the Norton version for Windows works you would not have a bootable exact copy on the second disk, but you would have a way to very quickly restore the entire system including the OS in the event that the main drive fails.

Faris.

 

[matt.simpson]

Okay, maybe I'm missing something here... but have you checked out:

http://www.acronis.com/

It's made by SW-Soft and there is a Plesk 8.0 module for it.

~Matt

 

[lpittman]

Yes its an option, but $700/machine? no thanks ... There must be an affordable option built into Linux ... like DD or something.

 

[jamesyeeoc]

This is just my 2 cents:

Yes, there are 'affordable' (ie. low or no cost) solutions such as 'dd', but there are limitations. The acronis company does have higher cost solutions which actually will allow you to have what you want when you want it. Even complete multiple server real time 'mirroring'.

Of course, limitations will also depend on your exact *nix distro...

$700/server - seems expensive, but for active $$ producing servers, I feel it is a worthy investment, even if you're not running Plesk on the production server. Implementing hardware RAID 1 (mirroring) should only cost about half that amount, but if it's not available at your DC, then what else to do?

 

[lpittman]

I definetly understand where your coming from, and do appreciate the feedback.

However, I am a small, very small company and just don't have those kind of resources. I figure attempting to offer ANYTHING for now is a good start. As my business grows, I'll grow my offerings, but for now, I have to work within my means.

Luke