Message-ID: <3D9A46E2.5040404@hanaden.com> Date: Tue, 1 Oct 2002 15:04:01 -0500 From: Hanasaki JiJi <hanasaki@hanaden.com> Subject: Re: RAID 5 Equation
Well 5 or 8 or 10 disks would require more storage for partity...
at 3 disks you are saying 1/3 is used for parity. is this linear? so:
60 gig usable = 90 gig total = 5 x 18gig?
Bill Clark wrote:
> RAID 5 parity is not on anyone particular disk. That would be RAID 3 that
> Mick is describing. In RAID 5 the parity is spread out and shared across
> all disks. That is why RAID is so popular. The odds are you won't loose
> more than one disk at a time. In most hardware RAID implementations if a
> disks dies. Then yanking the disk and replacing the disk will start the
> rebuild of the parity redundancy and within minutes you can be fully
> resillilent again. Or if you have a designated hot spare it can
> automatically take the place of a bad disk.
>
> If you have 3 disks and they are all 9GB disks then your effective capacity
> for that set is 18 GB. Three disks is the minimum number of disks allowed
> in RAID 5.
>
> Bill
> ----- Original Message -----
> From: Hanasaki JiJi <hanasaki@hanaden.com>
> Cc: Kclug@Kclug. Org <kclug@kclug.org>
> Sent: Tuesday, October 01, 2002 7:50 PM
> Subject: Re: RAID 5 Equation
>
>
>
>>So in Raid 5 the parity recovers data as well as identifying if data has
>>been corrupted? There was some equation, years ago that started:
>>- 1 bit parity identifies an odd number of bit errors
>>- 1 bit parity misses an even number of bit errors
>>- 2 bits parity .... BUT ITS NOT LINEAR, ITS EXP
>>
>>So what if the partity disk bites it?
>>
>>Mick Ohrberg wrote:
>>
>>>Theoretically, providing all the disks are the same size, it's the total
>
> sum
>
>>>of all disks, minus one disk (the parity disk).
>>>
>>>/Mick
>>>
>>>| -----Original Message-----
>>>| From: owner-kclug@marauder.illiana.net
>>>| [mailto:owner-kclug@marauder.illiana.net]On Behalf Of Jeremy Fowler
>>>| Sent: Sunday, September 01, 2002 4:27 PM
>>>| To: Kclug@Kclug. Org
>>>| Subject: RAID 5 Equation
>>>|
>>>|
>>>| Anyone know off hand the equation used to find the usable storage
>
> space
>
>>>| available with RAID 5?
>>>|
>>>|
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