Text 61742, 92 rader
Skriven 2010-08-12 15:29:22 av mark lewis (1:3634/12.0)
  Kommentar till text 61687 av August Abolins (1:123/789.0)
Ärende: raid 0 in xp, anyone?
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 AA> Anyone here have experience in configuring a Raid 0 configuration
 AA> in their XP system?  I'm just getting started to learn about it.
 AA> The idea would be to use the built-in software raid solution in XP.
 AA> However, I don't understand how raid 0 could truly suffice as a
 AA> backup solution.

RAID is /NOT/ a backup solution... it is a redundancy solution so that data is
not lost when one drive dies...

 AA> The software solution would require a "spare" hdd that is 
 AA> constantly connected and spinning.

R.edundant A.rray of I.ndependent D.isks == multiple spinning platters in
separate devices... so yes, you're looking at more HDs but you don't gain more
space for having them...

RAID 0   : striping
           provides improved performance and additional storage 
           but _no_ redundancy or fault tolerance. you "gain"
           storage space as the drives act as one.

RAID 1   : mirroring
           provides fault tolerance. each disk is a mirror of 
           the other. you do NOT "gain" storage space.

RAID 5   : striping and distributed parity
           provides improved performance and fault tolerance. you
           can loose one drive in the array and replace it for 
           data rebuilding. while the drive is down, the missing
           data can be calculated because of the distributed nature
           of striping and because the parity is also distributed.

RAID 0+1 : striped sets in a mirrored set
           combination of RAID 0 and RAID 1. requires four drives
           and always an even number of drives. provides fault
           tolerance and improved performance but at increased
           complexity.

RAID 1+0 : mirrored sets in a striped set
           combination of RAID 1 and RAID 0. requires two drives
           but seen commonly in a four drive setup for speed 
           benefits. also requires even number of drives. provides
           fault tolerance and improved performance but at increased
           complexity.

the key aspect of RAID 0+1 is that it creates a second striped set to mirror
the primary striped set. the array continues to operate with one of more drives
failed in the _same_ mirror but data is lost if drives on both sides of the
mirror fail.

the key aspect of RAID 1+0 is that it creates a striped set from mirrored
drives. in a failed disk situation, it performs better because all of the
remaining disks continue to be used and it can sustain multiple drive losses as
long as no mirror looses all of its drives.

RAID 5+1 : mirrored striped set with distributed parity.
           basically dual RAID 5s in a mirrored configuration.

the above paraphrased... check http://en.wikipedia.org/wiki/RAID for more
detailed information...

even with a RAID setup, you _still_ need backups... even with duplexing which
is using two controller cards to manage two mirroring RAID setups...

 AA> So.. if electrical damage occurs to the pc, then it is possible 
 AA> that BOTH hdd's could fail.

yes... or multiple controllers... the largest i worked on back in the day had
two hardware RAID controllers each managing 16 disks... yes, this was a SCSI
setup... so there were 32 drives in the cabinet with each group in a RAID 5
configuration... yes, you do gain drive space but not 

 AA> Personally, I like the idea of a temporary hdd connected via USB 
 AA> to do a clone or image.  But someone is telling me that the
 AA> logistics of raid 0 is much more efficient and "good enough".

NOT RAID 0... that only provides striping across the drives which makes them
act as one large drive... if you loose one you've lost it all... RAID 1 is what
you want if you want redundancy without the extra work...

of course, it should also be pointed out that software RAID solutions are not
as good as the hardware ones... this day in time, one must also watch out for
cheap RAID controller solutions as many of them require software for the actual
work... these are akin to winmodems... a true hardware RAID solution does all
the setup and management via the card's BIOS interface... the KEY method of
knowing if an array is software or hardware driven is that a true hardware
driven array is completely transparent to the OS which simply sees one large
drive.

)\/(ark

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