[CVALE] Backup/Imaging

[Steve Bibayoff]

Hello,

On 9/25/06, Pandora <cvale at synx.dyndns.org> wrote:
> Another backup possibility is RAID.  If you're going to go out and purchase all those backup hard disks, RAID is a system for automatically backing stuff up to them.

This has already been stated, but RAID != backup

>  It's got different levels, but I think most people use RAID 1, which is just automatic disk mirroring (also speeds things up because you've got two disks working for you at once!).

And also speeds things down(but not as bad as twice as slow), because
writes have to be done twice(to both disks).

>   Sometimes people use RAID 5 because it's more efficient in terms of disk usage, more than plain old redundant copies that is, but it's also somewhat processor intensive and hard on the disk.

Why would it be "hard on the disk"? Granted, w/ regard to raid 5, you
would have 1/n (w/ n=number of disks used in the raid device,
excluding spares) more writes per disk. And compared to the processing
power most people have, raid 5 is not very "processor intensive".

>  Depends what you're doing with it really.  I like RAID 5 because you can plug 5 disks all into one virtual disk 4/5ths their total size,

Depends on how many disks you have in your raid 5 device. 3 disks =2/3
their total size, 8 disks = 7/8 their total size, and so on.

> and if any single disk drive fails, you just pull it out, and put a new one in, and everything just works.

There's more to it then that. You also have to rebuild the array.
Having "hot spares" could make this process automated.


m2c

Steve