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Re: raid question

On Mon, Feb 10, 2003 at 01:11:15PM -0600, Dennis Wicks wrote:
> Greetings;            (Posted to LINUX-390 and debian-s390 lists)
> I came across an unsettling bit of info a while back.
> I was told that if you lose one volume of a raid set you can replace
> and the data will get rebuilt, but if you lose a second volume before
> you get the first one rebuilt you will lose all the data -- irretrievably!
> Is this true? Is there any reasonable way to get around it? Is there
> a reasonable alternative to raid?

This depens on your raid-level and on how you loose your disks.
Currently there are levels 0,1 and 5 supported. If you are using raid0
and you loose one of your disks (and loose means the disk really goes
away, no way to get the data on the disk back) you will loose data. If
you are using raid1, you can loose as many disks as you like, there
needs to be only on left which is still working. If you are using raid5,
then you will be able to loose exactly one disk. If you loose the second
one before the rebuild is finished then you will loose data. And you can
combine all this raid-levels. For example if you are using a raid10
(that means raid0 and raid1) with 4 disks, then you will be able to
loose 2 disks, before you will loose data.

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