Combining 2 hard drives into 1?

  • Thread starter Thread starter Sultin
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Sultin

I have two 40gig drives (both identical Western Digial, 7200rpm drives), and
was wondering if it's possible to somehow get Windows to read the C: as
80gigs, as opposed to two 40's?

I think I've read that RAID could do this, though I've never used this
before. Are there any disadvantages to doing this?
 
Sultin said:
I have two 40gig drives (both identical Western Digial, 7200rpm drives),
and was wondering if it's possible to somehow get Windows to read the C: as
80gigs, as opposed to two 40's?

I think I've read that RAID could do this, though I've never used this
before. Are there any disadvantages to doing this?
Click to expand...

If your motherboard bios supports this, you can use the two drives in a RAID
setup, with about 80GB storage space on drive C:. There's a huge
disadvantage though. If one of the drives goes bad, you lose your Windows
setup and all data files stored on drive C:
(note: If ONE of the two drives goes bad)

RAID can be used to prevent data loss also, but then you'd be stuck at 40GB
for drive C:
 
Mike T. said:
If your motherboard bios supports this, you can use the two drives in a RAID
setup, with about 80GB storage space on drive C:. There's a huge
disadvantage though. If one of the drives goes bad, you lose your Windows
setup and all data files stored on drive C:
(note: If ONE of the two drives goes bad)

RAID can be used to prevent data loss also, but then you'd be stuck at 40GB
for drive C:
Click to expand...

NOTE: Some RAID controllers also support JBOD (Just a Bunch Of Drives) or
Spanning. IOW, there are no optimizations or performance improvements
whatsoever, as would be the case w/ RAID0 (stripping). The controller
simply treats two (or more) drives as one single logical drive, which to be
precise, is closer to what the OP requested. In this case, you do NOT lose
all the data on the other drives, only the data on the failed drive (of
course). In fact, in some respects, spanning *could* be safer than a single
drive. Since data isn't typically written to the next HD until the current
HD is exhausted, it's entirely possible (depending on the size of the HDs
and number of HDs involved and the amount of space consumed) that a failed
HD has no impact whatsoever. IOW, the drive may have no data on it to
recover anyway.

Jim
 
Jim said:
NOTE: Some RAID controllers also support JBOD (Just a Bunch Of Drives) or
Spanning. IOW, there are no optimizations or performance improvements
whatsoever, as would be the case w/ RAID0 (stripping). The controller
simply treats two (or more) drives as one single logical drive, which to
be precise, is closer to what the OP requested. In this case, you do NOT
lose all the data on the other drives, only the data on the failed drive
(of course). In fact, in some respects, spanning *could* be safer than a
single drive. Since data isn't typically written to the next HD until
the current HD is exhausted, it's entirely possible (depending on the
size of the HDs and number of HDs involved and the amount of space
consumed) that a failed HD has no impact whatsoever. IOW, the drive may
have no data on it to recover anyway.

Jim
Click to expand...

Thanks for your reply.

My motherboard (a Shuttle AN35N Ultra) doesn't have have Raid, so I guess
that means I have to buy a raid controller for a PCI slot, right?

And is that all I need? Or is anything else required?
 
Sultin said:
Thanks for your reply.

My motherboard (a Shuttle AN35N Ultra) doesn't have have Raid, so I guess
that means I have to buy a raid controller for a PCI slot, right?

And is that all I need? Or is anything else required?
Click to expand...

JBOD sounds like what I originally wanted, but after some reading I see that
RAID-0 offers some performance increases. I think that's what I'll do.

After doing Raid-0 will I be able to do a clean install of XP on the drive?
 
Windows XP will ask you for third party drivers, press F6. So when
this happens press F6 and then later insert the drivers for RAID from
your motherboard manufacturer on a floppy disk.

Before this step, you must set your motherboard to recognize the ports
you have connected the drives you plan to use in RAID, as RAID ports
and not normal single ports.

Also, I think the drives must be identical, same model and capacity.
 
Also, I think the drives must be identical, same model and capacity.
Click to expand...

They're both Western Digital, 7200 rpm, and 40 gigs. HOWEVER, one drive has
an 8mb buffer and the other has a 2mb buffer.

Would this effect the Raid 0 setup?

Also, how does Raid 0 effect the speed everyday things like: booting XP
home ed., loading and using Firefox (w/broadband connection), etc?

Thanks.
 
Yeah, any time you access the hard drive you will notice a speed
difference. When opening browsers and surfing the net, you aren't
really using the hard drives so you won't notice a difference. This is
mostly the realm of your processor, RAM, and video card, Network Card,
Internet Connection Speed.

You will notice a big difference whenever you load and run hard drive
dependent things like games, video, audio, pictures, etc.

I could finally play games like Rome Total War smoothly when I switched
to RAID 0.

I noticed a big difference in games. I don't play many games anymore
but if you're a gamer you will benefit a lot from a RAID 0 setup.
 
Sultin said:
I have two 40gig drives (both identical Western Digial, 7200rpm
drives), and was wondering if it's possible to somehow get Windows to read the C: as 80gigs, as
opposed to two 40's?
Click to expand...

Yes, that is called spanning and XP alone can do that.
I think I've read that RAID could do this, though I've never used this before.
Click to expand...

Yes, but you dont need RAID to do that.
Are there any disadvantages to doing this?
Click to expand...

Yes, death of one physical drive will mean that you lose all the data.
If you dont span them, you obviously only lose one drive's worth of data.
 
I'm not sure about the 8MB and 2MB difference. I think it would matter
though. During critical times the slower one would fall behind the
other leading to errors. Go with 2 exactly identical drives unless you
want headaches later on. Your choice.
 
Yeah, any time you access the hard drive you will notice a speed
difference. When opening browsers and surfing the net, you aren't
really using the hard drives so you won't notice a difference. This is
mostly the realm of your processor, RAM, and video card, Network Card,
Internet Connection Speed.

You will notice a big difference whenever you load and run hard drive
dependent things like games, video, audio, pictures, etc.

I could finally play games like Rome Total War smoothly when I switched
to RAID 0.

I noticed a big difference in games. I don't play many games anymore
but if you're a gamer you will benefit a lot from a RAID 0 setup.
Click to expand...


Thanks, dude. I'm ordering the Raid controller now.
 
If you reformatted the two drives then you could set them up in RAID 0, if
your computer offers RAID, and you would have an 80 GB virtual harddrive. Of
course by reformatting you would lose your current OS and programs.
 
Rod said:
Yes, that is called spanning and XP alone can do that.


Yes, but you dont need RAID to do that.


Yes, death of one physical drive will mean that you lose all the data.
If you dont span them, you obviously only lose one drive's worth of data.
Click to expand...

Can volume spanning be done on XP Home?
 
I'm not sure about the 8MB and 2MB difference.
I think it would matter though.
Click to expand...

I doubt it.
During critical times the slower one would fall behind the other
Nope.

leading to errors.
Click to expand...

Nope, the worst that might produce is less the optimal preformance,
what you'd get with two identical drives. You wont get errors due to that.

And when you are using a decent OS, the OS level cache completely swamps the
drive cache, so you arent even going to see any performance deterioration either.
Go with 2 exactly identical drives unless you want headaches later on.
Click to expand...

There wont be any headaches.
Your choice.
Click to expand...

Yep, and if he want to take the extra risk with RAID0, say he is
doing proper backups of everthing that matters, it will work fine.

I'd personally span the drives at the OS level instead tho if he really
does want to be able to see a single 80G drive for some reason.
 
Rod said:
I doubt it.


Nope, the worst that might produce is less the optimal preformance,
what you'd get with two identical drives. You wont get errors due to that.

And when you are using a decent OS, the OS level cache completely swamps
the drive cache, so you arent even going to see any performance
deterioration either.

There wont be any headaches.


Yep, and if he want to take the extra risk with RAID0, say he is
doing proper backups of everthing that matters, it will work fine.

I'd personally span the drives at the OS level instead tho if he really
does want to be able to see a single 80G drive for some reason.
Click to expand...

Thanks for your reply.

Wouldn't spanning turn my virtual drive into 80gigs? If I'm spanning my 8mb
cache drive with my 2mb cache drive will this effect performance at all?
 
Ok, let's slow down a bit here, because there are some misconceptions being
stipulated here.

The two drives in RAID0 (or any other raid config) do NOT have to be
identical! All that will happen is that the pair's performance will only be
as good as the slower drive. That's all. Otherwise, you can throw any two
HDs into a RAIDO config and it will work. Any capacity, any buffer size,
any speed, whatever, it doesn't matter. Again, the ONLY consequence is that
performance can never be expected to be better than the slowest drive.
Obviously if you're planning to buy new HDs for a RAID config, it only makes
sense to purchase identical drives as a matter of economics.

Even if this wasn't the case, let's just say for the sake of argument you
did have to have IDENTICAL HDs, there's no such thing as two IDENTICAL HDs
anyway. The same model may experience ever so slight differences in
performance. You simply could never guarantee that any two HDs would behave
identically. Therefore, the controller is setup to always "wait" on the
completion of I/O requests from the slowest drive. If one if completed, and
the other is still working on I/O, the controller just waits until BOTH HDs
complete their respective I/Os, then returns.

As far as RAID (spanning, striping, or mirroring) working w/ XP, a hardware
RAID solution, such as using an on-board RAID controller or PCI controller
is INDEPENDENT of ANY OS! All the RAID functions happen at the BIOS level
of the controller. In fact, the controller has its own BIOS and HIDES the
fact that there is a RAID array from everything above it, including any boot
managers, partitions managers, OSes, etc. That's what makes a hardware RAID
controller so COOL! It works with ANYTHING, any utilities, any OSes,
because as far as these things are concerned, the controller present the
array as a single volume (even though the controller knows it may be a group
of drives working together, either spanned, striped, or mirrored) to support
it. Everything but the controller is OBLIVIOUS to the fact that a raid
array even exists.

And to get back to spanning vs. RAID0 (stripping), yes, stripping increases
performance because I/O requests can be split among two drives. However,
because these two HDs are dependent on each other to create a single LOGICAL
volume, if either fails, then you lose EVERYTHING. That's the inherent risk
w/ RAID0 (stripping) vs. spanning. Spanning provides NO performance
benefits whatsoever, it merely provides the CONVENIENCE of dealing w/
multiple HDs as ONE logical volume. Spanning is particularly useful if you
have a lot of SMALL HDs where the alternative might involve having a lot of
individual drive letters for all the partitions on those many drives.

So as long as you understand the risks of RAID0, fine, go for it.

Jim
 
Rod said:
You're welcome.


Yes, you would end up with a single 80G virtual drive.


Nope.
Click to expand...

I went to Disk Management, and right clicked on the "unallocated" space, but
I don't see the "New Volume" option, like I should. All I get it "New
Partition", "Properties" and "Help".

Could one of the needed services be disabled? I have the logical disk
manager services as well as volume shadow copy enabled already.
 
Sultin said:
I went to Disk Management, and right clicked on the "unallocated" space,
but I don't see the "New Volume" option, like I should. All I get it "New
Partition", "Properties" and "Help".

Could one of the needed services be disabled? I have the logical disk
manager services as well as volume shadow copy enabled already.
Click to expand...

XP Home doesn't Dynamic Disks, thus can't do volume spanning.
 
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