Partitioning a RAID 0 stripe array

  • Thread starter Thread starter Adrian Foot
  • Start date Start date
A

Adrian Foot

Hello,

I've been given advice that to partition a RAID 0 stripe array would
actually go against the work that RAID 0 striping does (i.e. the performance
increase gained). I was advised that the partition actually is on one drive
and doesn't spread so data is only ever written to that one drive whenever
that partition is referenced. Is this right? I'm not sure about it but the
person giving the advise is a Microsoft Consultant.

Is he mis-informed in this instance or is all the information that I've
found on the internet thus far incorrect?

Many thanks,

Ady
 
You can not partition 1 of the RAID hds and not do the other,this goes for
RAID 0 1 5 or 10.To set up youre RAID hds,plug in 1 SATA drive at a time,
boot to xp cd,press F6,select recovery,at recovery simply type:DiskPart In
DiskPart,create a partition,press ESC key,type:EXIT then power off,repeat
with other SATA drive,unplug 1st,or type:FORMAT C: /FS:ntfs Once thru,
type:EXIT Shut off computer,repeat with other,once both are thru,plug in
both,set up the array,boot to xp cd,install xp.
 
That hasn't filled me with confidence that the MS Consultant was wrong -
anyone else?
 
As an OS SEES any RAIDed disks as ONE physical disk, the same applies as to
a single, standalone disk, ie. it has to be partitioned and formatted before
use.
Also a single disk has to have at least one partition on it. So basically,
what that "consultant" said, is wrong.

To learn more about RAID, these might help:

http://www.acnc.com/04_00.html

http://www.prepressure.com/techno/raid.htm



--
Tumppi
=================================
Most learned on these newsgroups
Helsinki, FINLAND
(translations from/to FI not always accurate
=================================
 
Adrian said:
That hasn't filled me with confidence that the MS Consultant was
wrong - anyone else?
Click to expand...

If hardware RAID then you can partition to your heart's content. If software
RAID then the MS consultant is right sort of. Hardware RAID is built into
the controller and Windows only sees one drive for the entire array.
Partitioning is done after the array is created. Software RAID is done
through Windows and the partitioning is done during the array creation. This
is a simplified explanation. For the real goods you'd have to do some
searching on Google for how RAID works.

Are you using a RAID controller or the built in Windows RAID 0 support?

Note RAID 0 is not fault tolerant. You are doubling your chances of losing
data due to a disk problem. Unless you have a very specific need for RAID 0
it is not recommended. Even though many people tout RAID 0 as a performance
enhancement in reality there are better ways to speed up performance that
have less likelihood of data loss.
 
Kerry Brown said:
If hardware RAID then you can partition to your heart's content. If software
RAID then the MS consultant is right sort of. Hardware RAID is built into
the controller and Windows only sees one drive for the entire array.
Partitioning is done after the array is created. Software RAID is done
through Windows and the partitioning is done during the array creation. This
is a simplified explanation. For the real goods you'd have to do some
searching on Google for how RAID works.
Click to expand...

no, even "software raid" sits underneath windows; xp sees it as a single
drive (so does the bios, that's why booting still works). partitioning
works just as you'd expect, and does not undo the raid performance gain.

just look in device manager: it'll show a single "raid 0 volume", not
seperate drives. so does disk manager - one disk for the whole raid array.

------

I am not surprised at all that someone who identified himself as "a MS
consultant" got it wrong. "Those that can, do; those that can't cite
their references".

Rememeber the old proverb: free advice is worth every cent you paid for
it. [except here, of course!]
 
Many thanks for the quick and knowledgeable replies to this. I have to
admit that I questioned the guy himself on this because it didn't make
logical sense (and computers and their operations are VERY logical).

Glad to have cleared it all up - now to see what he says about it all.

Ady

Kerry Brown said:
If hardware RAID then you can partition to your heart's content. If
software
RAID then the MS consultant is right sort of. Hardware RAID is built into
the controller and Windows only sees one drive for the entire array.
Partitioning is done after the array is created. Software RAID is done
through Windows and the partitioning is done during the array creation.
This
is a simplified explanation. For the real goods you'd have to do some
searching on Google for how RAID works.
Click to expand...

no, even "software raid" sits underneath windows; xp sees it as a single
drive (so does the bios, that's why booting still works). partitioning
works just as you'd expect, and does not undo the raid performance gain.

just look in device manager: it'll show a single "raid 0 volume", not
seperate drives. so does disk manager - one disk for the whole raid array.

------

I am not surprised at all that someone who identified himself as "a MS
consultant" got it wrong. "Those that can, do; those that can't cite
their references".

Rememeber the old proverb: free advice is worth every cent you paid for
it. [except here, of course!]
Click to expand...
 
In fact another thing to note is that the AMD website section that describes
what RAID does doesn't mention anything about partitioning causing problems
(and it does mention a hell of a lot about partitioning in general).

Kerry Brown said:
If hardware RAID then you can partition to your heart's content. If
software
RAID then the MS consultant is right sort of. Hardware RAID is built into
the controller and Windows only sees one drive for the entire array.
Partitioning is done after the array is created. Software RAID is done
through Windows and the partitioning is done during the array creation.
This
is a simplified explanation. For the real goods you'd have to do some
searching on Google for how RAID works.
Click to expand...

no, even "software raid" sits underneath windows; xp sees it as a single
drive (so does the bios, that's why booting still works). partitioning
works just as you'd expect, and does not undo the raid performance gain.

just look in device manager: it'll show a single "raid 0 volume", not
seperate drives. so does disk manager - one disk for the whole raid array.

------

I am not surprised at all that someone who identified himself as "a MS
consultant" got it wrong. "Those that can, do; those that can't cite
their references".

Rememeber the old proverb: free advice is worth every cent you paid for
it. [except here, of course!]
Click to expand...
 
no, even "software raid" sits underneath windows; xp sees it as a
single drive (so does the bios, that's why booting still works).
partitioning works just as you'd expect, and does not undo the raid
performance gain.

just look in device manager: it'll show a single "raid 0 volume", not
seperate drives. so does disk manager - one disk for the whole raid
array.
Click to expand...

I have never actually set up a software RAID 0 array so I'll defer to you.
It's such a bad idea for so many reasons that I would never set it up. I was
going by the XP documentation. Reading it again I can see that you are
right. I was thinking of RAID 1.
 
Kerry Brown said:
I have never actually set up a software RAID 0 array so I'll defer to you.
It's such a bad idea for so many reasons that I would never set it up. I was
going by the XP documentation. Reading it again I can see that you are
right. I was thinking of RAID 1.
Click to expand...

RAID 0 is just fine, been using it for years. Definate performance boost,
for cheap. And it's no different than a single drive setup -- in either
case, if a drive fails then you loose the data - same diff, that's what a
backup is for.
 
Unfortunately it's IF EITHER DRIVE fails, you have total failure and
since you have 2, the RAID 0 "drive" will suffer hardware failure twice
as often.
 
RAID 0 is just fine, been using it for years. Definate performance
boost, for cheap. And it's no different than a single drive setup --
in either case, if a drive fails then you loose the data - same diff,
that's what a backup is for.
Click to expand...

In addition to Bob I's post software RAID requires dynamic disks which can
cause problems with many disk utilities, defrag programs, backup/imaging
programs and more.
 
Bob I said:
Unfortunately it's IF EITHER DRIVE fails, you have total failure and
since you have 2, the RAID 0 "drive" will suffer hardware failure twice
as often.
Click to expand...

oh boy, here we go again! "Twice as often"?

statistics not withstanding, if you own two cars is your chance of getting
into an accident twice as often?

or, if I have two friends, is it twice as likely that one of them will go
nuts and shoot me in the head. [well, that one might be true ;-)]

the MTBF of a drive is 10,000 hours. adding a second drive does not
change the mtbf of the first. running them continuously side-by-side and
the mtbf of the pair is still 10,000 hours [or 2 failures in 20,000 hours
combined run time - same diff].

Hey, drives DO fail. That's why we make backups.

But, for an extra $75 I can get a second 80GB HD and set the pair up for
160GB of noticably faster storage and system operation - that's pretty
much a no-brainer. In today's PC world, the HD is _THE_ performance
bottleneck.
 
You didn't put any real thought into that argument did you. What I said,
is exactly the real world effect. Thank you for playing.

Bob I said:
Unfortunately it's IF EITHER DRIVE fails, you have total failure and
since you have 2, the RAID 0 "drive" will suffer hardware failure twice
as often.
Click to expand...


oh boy, here we go again! "Twice as often"?

statistics not withstanding, if you own two cars is your chance of getting
into an accident twice as often?

or, if I have two friends, is it twice as likely that one of them will go
nuts and shoot me in the head. [well, that one might be true ;-)]

the MTBF of a drive is 10,000 hours. adding a second drive does not
change the mtbf of the first. running them continuously side-by-side and
the mtbf of the pair is still 10,000 hours [or 2 failures in 20,000 hours
combined run time - same diff].

Hey, drives DO fail. That's why we make backups.

But, for an extra $75 I can get a second 80GB HD and set the pair up for
160GB of noticably faster storage and system operation - that's pretty
much a no-brainer. In today's PC world, the HD is _THE_ performance
bottleneck.
Click to expand...
 
Back
Top