Clone disks

[Gregory J.Neumann]

Research carefully!  Depending on the distribution and kernel, you may or 
may not have to patch your kernel to support RAID.  I, also, have a 2 
disk SCSI RAID1 set up.  Simple software mirroring.  VERY FAST reads, as 
it nearly doubles the SCSI read bandwidth, but a bit slower on the 
writes, as EACH disk in the array must be written to separately.  But, as 
they say, it's a small price to pay.  You can actually have a RAID setup 
using different partitions on the same drive!  But other than a practice 
exercise, I don't see much use to it.  Sort of defeats the purpose.  
There are several "flavors" of software RAID supported by the Linux 
kernel, RAID 0, 1 & 5 being the most commonly used.  I leave it to you to 
figure out what they do! ;-)  The RAID HOWTO is very useful, and the mail 
list that is VERY helpful. Look back far enough in the archives and 
you'll find my silly-a** questions answered fully and courteously.  
 http://vger.kernel.org/majordomo-info.html should point you in the right 
direction.

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 12/1/01, 13:08:33, "[Darth] Snowbeam" <linux at snowbeam.dyndns.org> wrote 
regarding Re: Clone disks:


> Oh, now this does sounds interesting. It is pretty much what I am looking
> for. I'll look into it and try to test it out. Thanks for the info so
> far. Any other info and option are appreciated.

> On Sat, 1 Dec 2001, Darin Perusich wrote:

> > when you say "clone" do you mean mirroring? this can be accomplished
> > using software raid that's built into the kernel. if you have 2 drives
> > /dev/sda and /dev/sdb you can create a metadevice, /dev/md* of the
> > slices/partitions. see the raidtools man pages for more details, man -k
> > raid shoudl give you all the man pages. software raid is pretty simple
> > to setup and works well. i have a raid1 (mirror) device setup on 2 SCA
> > drives(hotswap). to test it i decided to pull one of the drives and it
> > just kept on kicking. pretty cool.
> >
> >
> > "[Darth] Snowbeam" wrote:
> > >
> > > Hi all, something I would love to see discussed here are clone disks. I 
am
> > > looking for the pros and cons of using clone disks. I actually want a
> > > better understanding of them. Over the last couple of months, I have 
found
> > > I now have some extra disks lying around that could be used as alternate
> > > boot sources should something happen to my primary disk. Some of my
> > > queries are:
> > >
> > > - Solaris allows for clone disks and alternate disk boot up. Does Linux?
> > > - Can clone disks be a form of back up? By this I mean, can a clone of
> > >   your primary disk and partitions be made on a daily basis?
> > >
> > > Usually I would go out an ddo the research myself, but as it's something
> > > that just came up, I thought I would pose my questions here as part of
> > > such research. Thanks for any info anyone can offer.
> > >
> > > ---------
> > > - [Darth] Snowbeam
> > >
> > > "It is not fear that keeps the elephant wary of the mouse, it is his
> > > wisdom that reminds him not to underestimate his opponent" -me

> ---------
> - [Darth] Snowbeam

> "It is not fear that keeps the elephant wary of the mouse, it is his
> wisdom that reminds him not to underestimate his opponent" -me