Intel RAID

[nigel.l.jones]

(Home PC question)
I have a Dell Dimension 5150 with
1 x 160Gb SATA II - Windows XP Media Center Edition 2005, photos,
music
1 x 120GB IDE - Vista x86 RC1, video recordings
The Intel Matrix Storage Manager/RAID support *IS NOT* enabled in the
BIOS

I jave just purchased
1 x 400 Gb SATA II

I would like to get to
320Gb RAID - Windows Vista x64 (160Gb original disk, and 160Gb of the
the 400 in a RAID 0 configuration for optimum performance in general
usage)
240Gb simple partition - likely move music/video here (a single 7200
is fast enough)
120Gb IDE disk - as is, for backup

Some assumptions
* The ICH7, disk config & intel storage manager support I have will
support the destination config
* Changing a disk that was installed without RAID installed to having
RAID installed (bios change) renders the disk unbootable, but does not
loose data

I'm most unsure about the "raid ready" (this just means bios enabled &
it boots?) -> RAID 0 transition

Would the following sequence likely work?
-> Enable raid in bios
-> Boot up vista RC1
-> install storage manager software
-> Use the raid sw to create the appropriate layout on the new 400Gb
disk
-> use a disk tool to copy the MCE partition over to the non-raid0
part of the 400Gb disk
-> bring the 160Gb disk into the raid config on the raid part of the
400Gb disk
-> Install Vista on the new RAID partition
-> Run Windows repair install on the MCE partition


What have I missed? (critical photos/docs/music are all backed up
already & current... )
I'm used to mid-range storage controllers that are pretty flexible
(well they are when you have 100's of disks to experiment with ;-)
...... )


Thanks
Nigel
vista at uk.me.cherrybyte (reverse the domain order)

 

[Hank Arnold]

RAID doesn't work that way. It works at a drive level only. It also
reduces the total amount of drive space available, unless you use RAID 0
(generally not recommended). Also, you will lose more disk space because
the lowest drive size is the one that will govern the total space.

For example, if you connected all three drives in RAID 5, you will end
up with 240GB of *total* space.

Also, if this is software RAID,, it is a *VERY* bad idea......

BTW, if you *were* to pursue it, you would most likely lose all data on
the drives that were added to an array.

Better read up on RAID. For what you have, it makes no sense at all.........

Regards,
Hank Arnold

 

[Tom Scales]

As far as I know, Raid configurations must be the entire disk, not
partitions. Also, the risks of Raid 0 are higher than the benefits. If
either drive fails you lose everything.

The performance gain is pretty small.

 

[nigel.l.jones]

As far as I know, Raid configurations must be the entire disk, not
partitions. Also, the risks of Raid 0 are higher than the benefits. If
either drive fails you lose everything.

I'm familiar with that feature! However I have automatic online backup
offsite, along with periodic DVD backup so am pretty well catered -
just the annoyance of failure.

What I'm finding is that I/O is a constraint (more than memory, CPU). I
hope vista will manage I/O better, but ulimately more disk capability
is required.

My experience to date has been mostly on mid/high end storage
subsystems with pSeries/AIX where it is indeed generally possible to
achieve the combination I outlined, with no requirement (although good
practice) on making the drives identical.

I would expect the operating system (windows in this case) to simply
see a 320Gb disk (which is all the smaller disk, and part of the larger
one), as well as a 240Gb disk (which is the rest of the larger one).
The 320 would have higher I/O capability as it's actually composed of
multiple disks. In a perfect world they'd be identical.

Now of course I am not in the slightest bit familiar with how Windows /
Intel Storage Manager works, so perhaps this is where the limitations
arise.

 

[nigel.l.jones]

From a little more digging it seems that the intel raid may not support
this.

If not another question ...

On my dell I can either have raid off or on. If off I think the
controllers report to be in "legacy IDE" mode.

If I want to take advantage of NCQ on the drives I have, should raid be
on or off (even though no raid arrays are enabled, and the disks
themselves are not raid managed).

Thanks!

 

[Folkert Rienstra]

If not another question ...

On my dell I can either have raid off or on. If off I think the
controllers report to be in "legacy IDE" mode.

If I want to take advantage of NCQ on the drives I have, should raid be
on or off (even though no raid arrays are enabled, and the disks
themselves are not raid managed).

And this question is prompted by what?

 

[Jan Gerrit Kootstra]

this.

If not another question ...

On my dell I can either have raid off or on. If off I think the
controllers report to be in "legacy IDE" mode.

If I want to take advantage of NCQ on the drives I have, should raid be
on or off (even though no raid arrays are enabled, and the disks
themselves are not raid managed).

Thanks!

Nigel,


I would suggest RAID off. If you do not use it, just turn it off. Just
to avoid strange behaviour.

If you still want to pursue your idea of having a bigger disc volume for
your Vista environemnt, did you try the disc manager of Windows Vista
itself (may be named different, lost my product key, so cannot reinstall
to help you)?


Kind regards,


Jan Gerrit

 

[nigel.l.jones]

Folkert Rienstra wrote:

And this question is prompted by what?

Performance. I have to reinstall the O/S anyway. New drives are being
released with NCQ support, yet it appears the ATA driver in XP does not
support NCQ. Best I can discover is that the BIOS needs to be set to
AHCI or RAID to enable this. If left at legacy NCQ is disabled, and the
potential 12-15% benefit cannot be realised.

I will experiment, but if anyone has definitive information it would be
appreciated.

Thanks

 

[Folkert Rienstra]

Nigel,


I would suggest RAID off. If you do not use it, just turn it off.

Just to avoid strange behaviour.

Obviously you have no clue of what you talk about.

 

[DaveW]

You CANNOT use a logical partition within a harddriveto set up a RAID array.
You must use two complete harddrives of the same capacity.

 

[Arno Wagner]

You CANNOT use a logical partition within a harddriveto set up a RAID array.

You must use two complete harddrives of the same capacity.

Wrong. But it is usually only possible with software-RAID.
The problem is that in order for this to work, the controller
has to be able to undertsnd the partition table. To the best of
my knowledge only software RAID ''controllers'' can do that.

However if the Vista software RAID (I assume it has software RAID...)
is only half as good as what Linux has, then using software RAID will
not even slow your system down to any significant degree.

One thing you likely cannot do is create a RAID ''in-place'' in
one step. What you would do in Linux is to create a degraded
array (only one disk), copy your data over and then add the
partition were your data was to the RAID as second partition.
THis allows you to copy data to a new RAID 1 and use the place
were the data was as part of the RAID 1.

Don't know whether Vista supports this. It is easy to support,
so if they do not have it, it is by choice.

Arno

 

[Jan Gerrit Kootstra]

Obviously you have no clue of what you talk about.

Folkert,


Explain your remark. (NL: Verklaar uw opmerking.)


Kind regards,


Jan Gerrit Kootstra

 

[nigel.l.jones]

Thanks for all the comments. I'm going to keep it simple. Don't even
want to go down the dynamic disk route, not enough confidence. Given
the marginal benefit will stick to tried and tested means. No raid,
although I will enable the raid option in the controller to benefit
from NCQ, and may still wander down the 64bit alley ;-)

regards

 

[Folkert Rienstra]

Obviously.

I have to reinstall the O/S anyway.

New drives are being released with NCQ support,
yet it appears the ATA driver in XP does not support NCQ.

So it will be up to the RAID driver then.

Best I can discover is that the BIOS needs to be set to
AHCI or RAID to enable this.

*If* true then that is utterly weird. That totally goes
against using drivers in higher order operating systems.

If left at legacy, NCQ is disabled and the
potential 12-15% benefit cannot be realised.

In OSes that use the bios. Current OSes use drivers.

And queueing usually only helps on very busy (multi-user/multi-
tasking) systems. 12-15% benefit may be nice in a production
environment but you may not even notice it on single user basis.