Mailinglist Archive: opensuse (1473 mails)
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Re: [SLE] A couple of questions about 2 hard drive systems
- From: malcolmb@xxxxxxxxx (Malcolm Brown)
- Date: Thu, 05 Aug 1999 10:52:17 +0100
- Message-id: <37A95ED1.D46661DC@xxxxxxxxx>
> >> What do you mean by poor mans sttripe array ? how is it diffrent from raid
> You mean they are mirrored?
Nope, stripped IDE drives contain stripes of the data to be stored. Imagine (and
I know this is a bit simplistic, but...) you had to store '010101'; then drive0
would hold '000' and drive1 would hold '111', ie. drive0 holds the odd elements
of the data to be stored, and drive1 the even elements.
Of course the physical implementation does not store each bit alternately, but I
don't know the granularity of the stripes, it might be each element is a sector
or a tracks worth of data.
> >Well, strictly speaking, it *is* RAID, but instead of a very sophisticated
> >SCSI controller doing the work, it's all handled by 'Block Devices/Multiple
> >Devices' in the kernel (software). NT can do it to.
> >I forget the RAID level that it emulates (either 0 or 1), but the effect is
> >that two physical disks become one volume, and they also run faster (about a
> >30-50% increase in speed). The drawback is that if one disk fails, *all*
> isint the data on both drives ?
The data is spread across both drives, but, as mentioned above, the chunks of
data are distributed alternately on one drive then the other. So if you loose one
drive, instead of loosing say the first half or the last half, you will loose
every other chunk, thus irretrievably corrupting the data you haven't lost.
> >data is lost. OTOH, if /home is going to be mounted remotely, this
> >shouldn't be a problem, really.
> >There is documentation on this that has been submitted to the LDP, check out
> >(Software-RAID HOWTO)
> > http://metalab.unc.edu/LDP/HOWTO/mini/Software-RAID.html
> >(Disk partitioning schemes)
> > http://www.nyx.net/~sgjoen/disk.html
> >-=|JP|=- (Resident GNUbie)
> >Jon Pennington | SuSE Linux 6.0
> >jon_pennington@xxxxxxxxxx | Kernel 2.2.7+
> >Kansas City, Missouri, USA | K6-2 350
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