RAID with caddies as back-up 2

[RayMunro]

I am investigating a possible back up solution for a small office. The network pcs will keep all files but OS's and programs on a dedicated pc running XP Pro. This pc will have (min) 250gb HDD in mirrored RAID. One HDD will be a standard internal. (D1)The second identical HDD will be fitted via a caddy and thus be removable.(D2) The back up will be via a third identical HDD.(D3) The plan is to remove D2 at the end of the day and replace with D3,and the next day to remove D3 and replace with D2 and so on.

I am given to understand that on a mirrored RAID each time the second mirror is replaced the system automatically re-writes the second disk to match D1.

Can anyone tell me how long it would take a PC running XP Pro, with 1024md ram and an AMD 3200 64 bit CPU to update the replaced HDDs? Thank you

 

[stduc]

Seems a bit dodgy and prone to error to me. I think you will have to experiment with this one. There are too many variables involved. Is it a software or hardware RAID? What are the drives real data transfer rates and write speeds?

Every time you replace the mirror you will probably be asked which way you want to copy the data. That could be confusing and fatal if ever you selected the wrong answer. Will the whole disk be copied or just the files/sectors that have changed? That will make a big different to the resynchronization time.

Have you considered just having the mirror as a permanent 'up to the minute' safeguard against hardware (disk) failure and having an additional backup routine to another device, perhaps a USB or network drive that could do regular backups to? As the mirror could either be software or hardware and permanent it may be a cheaper and simpler solution.

I did have an 80Gb mirror (RAID 1) fail once (I can't recall the configuration - but it was a hardware RAID) I think it took about 30 minutes after replacing the failed drive for the rebuild to complete and the machine to boot. (I doubt that helps you much though!)

 

[smah]

In addition to what stduc is saying about actually doing it, what's the point of this proceedure? The removed drive really isn't a 'backup'. It's only part of an array that may or may not be able to be rebuilt in the event of disaster.

 

[RayMunro]

Thanks for your replies.

The idea was to have an easy back up tht staff could do in a few moments. With the tape back up they ofton "forgot" because it took so long.

It looks like I'll be keeping the tape.

Thanks again

 

[stduc]

Backups have to be automated, or they just don't happen in the real world.

Two possible solutions for you to consider.

1. Automatic backups using a server. Backup software such as trueimage can do this. Simply tell users to turn off their screens when they go home and use a server script to turn off the PC's after the backup.

2. Add network storage to your LAN and backup to that. One way to automate the backup would be to have a scheduled incremental backup on shutdown for each PC.

There are many other solutions possible as well.