We need a small business storage system that can expand in capacity by
adding more drives. We have used RAID5 type systems in the past, but
they suffer the limitation that drives could not (5 years ago) be
added to the cluster later to increase capacity, at least not without
reformatting.

We're thinking some kind of NAS box or SATA raid box or similar must
surely support adding drives dynamically. Some downtime would be
acceptable immediately after adding a drive, FYI.

The target OS is windows, NTFS. We need reasonable data throughput, so
100Mbs ethernet might be OK, or fireware or even a PCI adapter. High
speed SCSI is definitely not needed.

Capacity we think should be around 600Mb starting, and expanding to 2TB.

We don't need guaranteed uptime and other enterprise type features.
The box is to be used in an important part of the business, but it's
not colocated in the data center.

Cost $1k to $5k seems reasonable.

Recommendations for suitable products ?

http://h18004.www1.hp.com/products/servers/proliantstorage/sharedstorage/sacluster/index.html
fits your spec and price

You didn't mention if you needed a tower or rack configuration - but
here's a rack mounted solution.

Cost per MB is cheaper with SATA drives than with SCSI drives.  I
prefer SCSI (for performance reasons) in a business solution, but SATA
should work just fine for what you're looking for.

As to adding to an array once it's been created, SCSI RAID controllers
will be more robust and focused on expandibility/configurability with
minimum downtime.

Regardless, for a rackmount enclosure, I would recommend something like this:
http://www.techonweb.com/products/productdetail.aspx?id=B68275&src=FG

$2,813 for an 8-bay SATA enclosure (connects to host machine via SCSI
U16 - includes adapter)
6x$400 ($1,500) for 6 SATA drives (for RAID 5)= 2.0TB of storage

Total Cost = $4,313

You could definitely go more expensive, but I'm not sure your needs
require it.  I would definitely fill the remaining two bays so that
you can have global hotswaps available.

If you're in GA and need hand-on help, let me know and I can provide
specifics along with install services.

As I said in my posting, high speed scsi is definitely not needed.
SATA is ideal because of cost.

I prefer to avoid SCSI to the host also, because of the infexibility
of the cabling involved. Firewire is good enough.

The most important thing is that we can add drives later and expand
capacity without reformatting. I need to know precisely which solution
offers this and how it works.

Sorry for my math being off on the drives in the previous post (it had
been a long day).  The actual total should have been $5,213.

Regardless, it sounds like you're looking for a consumer class device
that will deliver enterprise class features (a tough bill to fill).

There are many different ways you can go with this, but I don't think
that the demand is such yet to warrant companies building 1394 RAID
devices with 2TB RAID5 capacity.

If you *are* able to find one, it may be by such an obscure
manufacturer that it'll be almost impossible to support if something
ever goes wrong with it.

When you say that SCSI cabling is not flexible enough, can you  be
more specific?  Are you talking about physically routing it from one
device to the other?  Or are you talking about terminating, SCSI ID's
and such?

Also, is this going to be rack or tower mounted?  

Finally, I really don't understand your final statement about having
to reformat when you add drives.  I've been doing this type of work
for 15 years  and the worst I've seen (when adding capacity only) is
that you actually have to down the server for the changes to take
effect (when you're expanding an array).  However, most cards now days
offer online capacity extension.  If in doubt, just look through the
specs for the controller card.

If you could give me a little more information, I'd love to help you
out.  But as I said earlier, because of your storage requirements, you
may need to step into an enterprise class product - even though you
may not need/use all of the functionality.

this is primarily for a desktop workstation application and I've
always found that SCSI cabling is klunky. I imagine putting the box on
the floor out of the way and also to cut the noise. Given that I want
avoid rackmount, and also hotswap is not needed (per my original post,
it's not a 24x7 uptime situation)

www.micronet.com seems to have somewhat suitable devices. Opinions?

Now, onto the critical question of capacity expansion. I understand
the array can be expanded by adding drives, but does anything need to
happen at the OS level? Does the RAID controller understand an NTFS
disk and expand the partitions accordingly?

I'll answer your questions backwards here...

As to online capacity extension and partitions...No, a RAID array
controller will not modify the partitions on the disk.  It will either
look like (through the OS) that partition/logical drive is sitting on
a larger physical drive, or you'll have a whole new physical drive
altogether (if you create a new array).

If you want to expand your partitions without having to backup,
resize, restore, you can always use PartionMagic (Symantec owns them
now).  **WORD OF WARNING** Make sure you have a good backup before
using this program.  It works and I highly recommend it, but if
something goes awry (or you screw something up), very high potentional
for losing data.

As to the the site you recommended, the only firewire/1394 device I
see have 5 bays.  If you populate this drive out with 500GB drives,
you can achieve 2TB RAID5.  However, the site doesn't say whether or
not 500GB drives are supported.  Also, I don't understand where they
say, "Up to 2.0TB raw storage capacity utilizing 300GB drives."  With
5 bays at 300GB a pop, I believe that's only 1.5TB (1.2TB RAID5). 
Also, ordered in their 2.0TB configuration, you'll only receive 400GB
drives which will put your raw storage at 2.0TB, but your realized
storage w/ RAID5 at 1.6TB.

It's late, maybe I'm reading something wrong, but their math seems off...

Oh ya...

SCSI cabling used to be pretty bad (maybe around 10 years ago).  It's
late I'm probably off a little on my terminology, but back then you
were dealing with a 50-pin to centronics type connector for SCSI I. 
These cables were real thick and were kind of a pain.

But the SCSI3 cables out now are a completely different story -
they're much more flexible (and smaller in diameter).

As to the noise of the device/enclosure, your interface type won't
affect this.  Going with 7.5K vs 10K drives will.  Number of fans
will.  Number of drives will.  Manufacturer of drives will. 
Construction of case will.  Power saving capabilities will.  Interface
will not (they're silent to begin with - unless you can hear your IDE
controller).

Okay, I've spent some time reading through this question trying to
fathom what you're trying to do with a workstation application that
will need up to 2TB of storage.. surely something with that capacity
of data would be better off with a database server managing the
information?  And if the application indeed requires a Windows
workstation with raw access to files, then the performance hit will
likely to be severe, you might want to look into alternitive methods
of solving the same problem.  More information on the actual problem
might deliver a better solution.  Just a suggestion.

Our app *is* the database, effectively. Complicated to explain why we
don't shove the data into a database, so suffice to say that we're the
developer of the software and this query is helping us refine what
storage hardware to recommend to our customers. Normally that would be
easy, but they are SMBs with small budget and we need to dynamically
expand the storage (thanks for the comments about partitions earlier.
That confirms my suspitions).

I'm thinking a cheap SAN box is the way to go. Forget SCSI/Fireware.
If we have 100Mb ethernet (1G perhaps?) that's going to be quick
enough for this app.

So, is there a SAN box that offers RAID, is aimed at SMB, and can have
volumes added on-the-fly. I'm thinking because it's SAN it could be
expanded because the access if via SMB, which doesn't know about
physical partitions.

XSan from Apple will do it, but at a higher cost than you want to pay.

http://www.apple.com/xsan/

I'd guess around $8K depending on your needs, but it can expand to
around 2,000 Terabytes.

Basically, you are looking for a Veritas File System for NTFS prices.

Aha, so can you confirm there is no cheap device that I can resize
later by adding more drives? The XSan looks good, but too pricey as
you predict. Any others?

supposedly this thing expired, but there's an easy way to do this,
unless you need the actual filesystem to be local and NTFS.

You can use a remote disk server to do this and use microsoft SMB
filesharing over a highspeed network (gigabit or even faster, say
infiniband for throughput) - tho really gigabit has a theoretical max
of 120mb/s (actual range is 100mb/s). Infiniband is 10x faster (and
alot more expensive but possibly worth it - your disks will be the
bottleneck with infiniband unless you have a huge SAN.)

The basic idea here is to setup a linux disk server running lvm2 or
EVMS to allow expandable virtual volumes and filesystems with hotswap
SATA bays on a multiport SATA card (3ware or LSI or otherwise), and
use SAMBA networking to share the disk over the network. Disks can be
added at whatever time, and here's the kicker, using MATURE
filesystems in linux (say not ext3, the standard linux fs, but like
XFS, which is SGI's extremely great and much better tested fs) you can
expand the filesystem LIVE when you add disks.

email me at mattix-answers-google at  sizone.org  about this if you
want more details, and I can give you some more specific details on
likely pricing and what not.