Re: Create a raid on sparc guide
> For learning. My employer lost a day's mail for about 3000 people
> recently due to a failure of a RAID 0+mirror setup (two separate RAID 0
> systems, I believe each having 4-drive arrays). A drive in the main
> RAID 0 array failed, and then a drive in the mirror array failed when
> restoring. (The chances of this are pretty slim, but they might have
> been lower if there was a RAID 1+0 setup instead of two RAID 0's.) So
> this pair of RAID 0's constituted UAVED, "unreliable array of very
> expensive disks". Very expensive due to the loss of data and the labor
> to go back and restore from tape old mail stored on this server system.
> (It's an IMAP mail repository.) A loud prompt for me to learn about
> -- SP
I am sorry, but I have to ask, why did your employer not go with a
RAID-5 setup with extra disks? I am guessing that because of the number
of drives (4, aka 2 ide chains?) you are using IDE/ATA? So why not
something like 4 x 40 gig drives in RAID 5 with 1 spare drive? I am
talking a bit out of my ass, but curisosity compels me to ask...
This is my first experience with raid and although there is some very
nice documentation (
is the best I have found), for a person to setup raid on the cheap or on
a sparc they have not addressed all the issues.
On the Cheap: I do not have extra disk laying around to install debian
on to transfer to a raid later. So I instead installed debian on a
partition that I would later use for swap. Also as I did not have a smp
or a raid kernel availible, and was not connected to a network I had to
compile my own kernel with raid *(not as a module)* and smp.
On the Sparc: SILO is a program that has jack for documentation. I am
still working to figure out the limitations of SILO.
My thoughts are that a short guide should speak to: 1. Types of
applicable Raid (linear, 0 and 1 for the SS and just about everything
for the ultras I think) 2. Partitioning 3. Installing the a bare bones
OS and compiling a new kernel 4. Setting up the RAID and transfering /.
The version of fdisk that comes on a debian stable disk 1 has an issuse.
If you try to put a swap as the first partition on a drive fdisk tells
you that you are wasting your time because you are destroying the
partition table. However if you try to make a partition of type fd
(linux raid autodetect) you do not get this warning, although the you
are destroying the partition table. This cost me something on the order
of 2 hours to figure out and I was unhappy when it was over.
It is worth not that the bandwidth of a SS20 is 10 MB/sec (I think) so
performacne increases for most user will not be incredibly dramatic. I
setup my machine in RAID 0 because I did not have enough room a single 1
gig drive to anything interesting, so my choices became linear or RAID
0. Linear is not very sexy, and most of the issuse are exactly the same.
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