Can RAID Controllers act as non RAID controllers?

  • Thread starter Thread starter Peter Olcott
  • Start date Start date
P

Peter Olcott

I want to build a software based RAID system, and need to
have simultaneous access to 24 drives. I will probably go
with SAS controllers and SATA drives. From what I recall
most drive controllers can only handle 4 drives, and most
motherboards only have four fast PCI express slots. I need a
way to hook up 24 drives to no more than 4 slots. One easy
way would be to get a SAS controller card that can handle 24
drives without specifying a RAID level. Can this be done?
 
kony said:
Yes, if the card supports single drive spans. That's a
very
common feature on lower end raid cards but for one that
can
handle 24 drives I don't know.
Click to expand...

I could not find anything about this on google [single drive
spans]
[single drive span] [drive span]
 
Peter said:
I want to build a software based RAID system, and need to
have simultaneous access to 24 drives. I will probably go
with SAS controllers and SATA drives. From what I recall
most drive controllers can only handle 4 drives, and most
motherboards only have four fast PCI express slots. I need a
way to hook up 24 drives to no more than 4 slots. One easy
way would be to get a SAS controller card that can handle 24
drives without specifying a RAID level. Can this be done?
Click to expand...

This one mentions support for "single disk". 8 ports.
Fastest IOP available as far as I know. About $600 each.

http://www.highpoint-tech.com/USA/series_4300.htm

Paul
 
kony said:
kony said:
On Thu, 18 Sep 2008 05:47:43 -0500, "Peter Olcott"

I want to build a software based RAID system, and need
to
have simultaneous access to 24 drives. I will probably
go
with SAS controllers and SATA drives. From what I recall
most drive controllers can only handle 4 drives, and
most
motherboards only have four fast PCI express slots. I
need
a
way to hook up 24 drives to no more than 4 slots. One
easy
way would be to get a SAS controller card that can
handle
24
drives without specifying a RAID level. Can this be
done?


Yes, if the card supports single drive spans. That's a
very
common feature on lower end raid cards but for one that
can
handle 24 drives I don't know.
Click to expand...

I could not find anything about this on google [single
drive
spans]
[single drive span] [drive span]
Click to expand...

Look at the instruction manual for the card you're
considering.

A multi-drive span just creates a single logical volume
that
is the sum of the individual drive members. For example
two
250GB drives in a multi-drive span would create a 500GB
logical volume. Unlike RAID0 it doesn't stripe data
across
both drives, it starts at the begining of one and starts
on
the second after the end of the first.

A single-drive span is one that only has one member in it,
is typically how a drive is used on any non-raid
controller.
Click to expand...

I must keep the drives separate, yet not in any RAID
configuration. What I must end up with is drive letters "C"
through "Z".
 
Somewhere on teh intarwebs "kony" typed:
If the card supports 24 single drive spans, you would end up
with drive letters C through Z. If the manual does not make
both the factor of using single drive spans, AND supporting
24 of them clear, contact the manufacturer.
Click to expand...

Is this feature not what they call "JBOD" (Just a Bunch Of Disks)?
--
Shaun.

DISCLAIMER: If you find a posting or message from me
offensive, inappropriate, or disruptive, please ignore it.
If you don't know how to ignore a posting, complain to
me and I will be only too happy to demonstrate... ;-)
 
I don't think so. I think that JBOD links the disks together
into a single virtual drive.
http://www.pcguide.com/ref/hdd/perf/raid/levels/jbod.htm
Click to expand...

Some people wholeheartedly disagree about this terminology :-)

Spanning is spanning (and usually a bad idea for harddisks).

JBOD is 'just a bunch of disks'. Meaning, that you should be able
to add or remove just any of them, if you whish to do so.

I for one have never seen a good argument for calling a spanned
diskset JBOD. Nor do I know of a (more) proper term to describe a
bunch of independant disks that happend to end up in a single
enclusure :-)
 
Somewhere on teh intarwebs "Gerard Bok" typed:
Some people wholeheartedly disagree about this terminology :-)

Spanning is spanning (and usually a bad idea for harddisks).

JBOD is 'just a bunch of disks'. Meaning, that you should be able
to add or remove just any of them, if you whish to do so.

I for one have never seen a good argument for calling a spanned
diskset JBOD. Nor do I know of a (more) proper term to describe a
bunch of independant disks that happend to end up in a single
enclusure :-)
Click to expand...

I have to agree with you Gerard. Why would you call a spanned set of disks
"just a bunch of disks"?

It is what it is, just a bunch of disks.

Cheers,
--
Shaun.

DISCLAIMER: If you find a posting or message from me
offensive, inappropriate, or disruptive, please ignore it.
If you don't know how to ignore a posting, complain to
me and I will be only too happy to demonstrate... ;-)
 
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