Filesystems, Disks and Memory

After reading some books, I came across this idea of having a duplicate of your current hard drive on another second hard drive so that if the first hard drive happens to crash, the system can be up and running in quickly

now, is there anybody in here who uses this method at work?? If there is, I really would appreciate it if you can clarify for me the disadvantages of using this disk mirroring thing. I would also like to know if disk mirroring is a good idea at all.

Back when my father did this - the answer would be no - it was too expensive.

Now, it too expensive not to. If you have a server that HAS to be up one of the first things you want to do is to have your OS drives mirrored.

Disadvantage - writes to multiple drives

Advantages - reads from multiple drives - protects server from down time - allows (possibly) on-line backups with no down time for users.

so, basically what your saying is that it is a good idea to do disk mirroring and that the disadvatages doesn't really over shadow the advantages, right???

and please, would you mind telling me the steps used in making a disk mirror??? just the general steps. The linux red hat book I read that talked about mirroring did not elaborate much on it. It just talked about simple steps and am thinking "there has to be more to it that this"

please, if you have more information, I would appreciate if you share them all with me.

also how can I do it so that I can automate the mirror disk to take over if there should be a crash or failure of the original disk????

Basically, it almost mandatory these days - most OS have some type of free software to do it.

Check out this link on Redhat .

Can't give you more than that since I'm not running it at the moment.

Your last question - you don't tell it to fail over - it should fail over by itself via the hardware or software (see the link).