RAID level 5 question

[Rodolfo J. Paiz]

At 05:14 3/31/2004, you wrote:
>I'm thinking about setting up a software raid level 5.
>Is it possible to start with 3 HDs and then later add more?
>I mean, without loosing the data on the first 3 HDs.

Yes, on most *good* hardware RAID cards and also (I think) on Linux 
software RAID.

What you do is add a disk, then use the RAID tools to add the disk to the 
array. You now have a larger array, with some wasted space because the 
filesystem (/usr, for example) did not get expanded. Finally you use a tool 
like GNU parted (included in Fedora) to resize the filesystem.

However, you're using RAID 5 to prevent data loss. And although I've used 
parted for years without a single problem, you should never mess with 
filesystems or other critical schema without first backing up all your 
data. But since your RAID 5 may just be too big to easily back up, most 
people then proceed to resize the filesystem without a backup. And probably 
1 in 1,000,000 people is going to lose data.

As the man said, "you pays your money and you takes your chances."


-- 
Rodolfo J. Paiz
rpaiz at simpaticus.com
http://www.simpaticus.com