Re: PE2950, RAID 0, failed disk

["Ben Holland" <user=122@nabble.blu.org>]

 I didn't think that half of each file was on each disk, I thought that there 
were fairly large swipes of files, like say perhaps even per page or every 
100MB, the first 100MB was written to one disk, the next to the other and 
back and forth, or even pages, i-nodes, file structure, the whole deal. 
Anyone got a fun link on how RAID works in a real work app since I learned 
this sorta stuff only in the theoretical sence? ~Ben 

On Thu, Mar 6, 2008 at 5:57 PM, Jarod Wilson <[hidden email]> wrote: 

> On Thu, 2008-03-06 at 16:11 -0500, Ben Holland wrote: 
> > Alright, I was going to say something about how RAID 0 just stripes with 
> no 
> > parody, a RAID 1 mirrors, so you get a whole drive of redundancy RAID 5 
> is 
> > stripe with parody so you need 3 drives minimum. If you loose a RAID 0 
> you 
> > lost half of your data, you can't recover from it, and chances are you 
> lost 
> > all of the other side as well because your file system is totally hosed 
> > (though could someone please verify that). 
> 
> Yes, that is correct, the file system is completely hosed, you've 
> probably got zero chance at recovery without taking the entire array, 
> including the original failed disk, to a recovery specialist. 
> 
> NEVER EVER EVER use RAID0 for data you can't afford to lose. It should 
> only be used when you need high-performance short-term storage (such as 
> for a build system or test system that does heavy disk I/O, but the data 
> doesn't need to be kept around). 
> 
> 
> > On Thu, Mar 6, 2008 at 3:45 PM, Vince Kimball <[hidden email]> 
> wrote: 
> > 
> > > I believe RAID 0 has no redundancy, so a single drive failure destroys 
> > > the volume. 
> > > 
> > > Scott R. Ehrlich wrote: 
> > > > I have a Dell PowerEdge 2950 with PERC 5/i, and 6 disks.  Two disks 
> > > > have one logical volume via a hardware RAID 1 and consist of CentOS 
> 5 
> > > > 64-bit; the remaining four comprise a logical volume via a hardware 
> > > > RAID 0, and is all user data. 
> > > > 
> > > > One drive on the RAID 0 went bad.   I removed it while the system 
> was 
> > > > on, tried a reboot, and the system hangs at RedHat Linux... Starting 
> > > > 
> > > > I tried to boot from a Fedora 8 CD, which sees the boot drives fine, 
> > > > but not the RAID 0 partitions. 
> > > > 
> > > > Visiting the PERC controller setup claims the RAID 0 volume is 
> > > > unavailable, or something similar, though it is defined, with one of 
> > > > the disks labelled as missing, since I removed it from the system. 
> > > > 
> > > > How do I get the partitions on the RAID 0 setup back?   I have some 
> of 
> > > > the data, but need the rest, if possible, and the remaining three 
> > > > disks appear physically healthy.   I'm also going to work with Dell 
> > > > for some answers, and I've done a lot of googling. 
> > > > 
> > > > Thanks. 
> > > > 
> > > > Scott 
> > > > 
> > > 
> > > 
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> > > 
> > 
> 
> 
> -- 
> Jarod Wilson 
> [hidden email] 
> 
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