Raid 1 Problem

[TerminalX]

I want to secure my files for good. I turned to raid 1 solution for this (Mirroring). But i think that i want something more than this.I have a 40Gb hdd in my pc.I just bought 2 more 40Gb hdd and a promise raid controller.I have one Hdd tray ( removable hdd) and i want to be able to put in the one hdd i bought and the other day the next one.My question is if the mirroring will be able to work with that.Example: I have hdd A inside my pc, and i bought hdd B and Hdd C.With the Hdd tray i put one day B Hdd to have a mirroring of A Hdd.When i turn off my pc i'll remove B.The next day i'll put C on hdd tray.Will it continue to mirroring normal??Because it has data 2 days old than other.I want with this way to secure 1 day loss back up if my Pc Collapse totaly ex.FIRE.. Any other solutions if this cannot be done??? Thanks and sorry for my English .. )I'm not good in Grammar.. )))

 

[lunitic]

Theoretically it will work.
However, it seems not very practical to me: when you insert a new mirror drive the RAID controller will detect the mirror is broken, and you will have to rebuild the array. This will take some time (it essentially amounts to making a complete copy from the broken mirror to the new drive), during which the system is unusuable (it is done before booting, in the Fastrack bios extension).
It is possible to rebuild the array 'on the fly', if a hot-swappable drive is present, but that would still require you to define the replacement drive as hot-swappable every day before breaking the mirror, then breaking the mirror. I think. It would still require the mirror drive to be synchronised, during which the performance of your system will suffer. It would mean that all three drives are in the system at one time, making the solution vulnerable during that time.

Besides, this solution doesn't help against the most likely source of data-loss: user error. Well, that is untill the second drive is synchronised, therewith destroying any old data. You need to keep more backup generations for that.

If your data is that valuable, you'll need to invest in a tape drive. Then you'll need to implement a backup-strategy. How many generations are you going to keep; how long must you retain your data; where are you goint to store your backups.

Remember: mirroring is meant to make a systems up-time as high as possible, not for backup-purposes.

 

[sjonnie]

A better solution would be to invest in a tape streamer that can make an automated backup of your system. If you wanted to keep the data off-site then you could easily have 2 tapes and swap them at regular intervals.

The reason is that harddisks are most susceptible to damage during transit so constantly swapping them and/or transporting them about is going to increase your risk of damaging the disks and loosing data. Tapes are specifically designed for data security, backup and portability.

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