Is there such a thing as a relatively inexpensive box (up to a few K$,
say) that can hold a huge amount of ram, like 200-1000 GB?  It doesn't
have to be battery backed or anything like that, but it should have
ECC or at least parity.  The application is a high traffic database
cache.

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In article <7x8xpqokbq.fsf_-_@ruckus.brouhaha.com>,
Paul Rubin  <http://phr.cx@NOSPAM.invalid> wrote:
>Is there such a thing as a relatively inexpensive box (up to a few K$,
>say) that can hold a huge amount of ram, like 200-1000 GB?  It doesn't
>have to be battery backed or anything like that, but it should have
>ECC or at least parity.  The application is a high traffic database
>cache.


Google "solid state disk" and you might want to add "-CF" to avoid all
the people that want to sell you CF cards.


I'd figure 100 bucks/GB as a WAG for price. How much money do you have?




--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

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adykes@panix.com (Al Dykes) writes:
> I'd figure 100 bucks/GB as a WAG for price. How much money do you have?

That amount of bucks/GB is reasonable.  A $50K expenditure for this
application might not be out of line, if it resulted in getting 400GB
of ram ($10K for the box and 40k for the ram).  All the "solid state
disk" applicances on that scale I know of cost a heck of a lot more
than that.

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Zak <jute@zak.invalid> writes:
> I'd think $50K is way too low. You are talking a specialty product
> (what interface does it use...).

Just about anything--PCIe, Infiniband, heck, even USB2 or Firewire.

> Also the commecial life is short - it will have to move along with
> available DRAMs.

Is that a big deal?  What is so high tech about this?  It's just a
bunch of dimm sockets on a board, right?  Giga-byte makes a PCI
ramdisk with four dimm sockets for $50, but it can only take 1GB
dimms.  I just want something like that but a lot bigger, maybe
multiple boards, and able to use 2gb or 4gb dimms.  Let's say a 1U
rack box containing a board with 32 or 64 dimm sockets.  A few of
those with 2gb dimms (around $140/GB right now with ECC) and I'm
there.

> Can't you use a bunch of PC's? Even then you have limited choice
> because of the ECC/parity requirement. Though that could be done in
> software of course (modulo the small chance the checking software is
> going to be hit).

What PC's exist that can take more than 16GB?  I'd have to use dozens
of them to get 500 GB of ram.

I also notice that flash memory in the form of SD cards is now around
$25/GB in 4GB cards:

http://www.zipzoomfly.com/jsp/Produ...ctCode=82502-19

I wonder if there's some way of sticking 128 or so of those in a box.

Thanks.

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Paul Rubin wrote:
 
>
> Just about anything--PCIe, Infiniband, heck, even USB2 or Firewire.

For you that's okay, for others maybe not. That divides up the market.
 
>
> Is that a big deal?  What is so high tech about this?

It means the manufacturer can sell it for a few years at most, then has
to change the design and so on. Doesn't make things cheap.

> It's just a
> bunch of dimm sockets on a board, right?  Giga-byte makes a PCI
> ramdisk with four dimm sockets for $50, but it can only take 1GB
> dimms.  I just want something like that but a lot bigger, maybe
> multiple boards, and able to use 2gb or 4gb dimms.  Let's say a 1U
> rack box containing a board with 32 or 64 dimm sockets.  A few of
> those with 2gb dimms (around $140/GB right now with ECC) and I'm
> there.

Where do you buy cheap 2 or 4 GB dimms? Not a commodity product either.
And it is not just sockets - it is drivers too. Running everything at
lower speed may help. But again this needs research.
 
>
> What PC's exist that can take more than 16GB?  I'd have to use dozens
> of them to get 500 GB of ram.

Yes. And PC's are cheap compared to a custom design for a very narrow
market.

> I also notice that flash memory in the form of SD cards is now around
> $25/GB in 4GB cards:
>
>   http://www.zipzoomfly.com/jsp/Produ...ctCode=82502-19
>
> I wonder if there's some way of sticking 128 or so of those in a box.

There is (look up USB card reader). Then go and look at the speed and
durability. And look at your ECC requirement again. It is cheap, yes. But...


Thomas

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In article <44521782$0$6423$2e0edba0@news.tweakdsl.nl>,
Zak  <jute@zak.invalid> wrote:
>Paul Rubin wrote:
> 
>
>For you that's okay, for others maybe not. That divides up the market.
>
 
>
>It means the manufacturer can sell it for a few years at most, then has
>to change the design and so on. Doesn't make things cheap.

I don't see anyone buying a big RAMdisk without ECC and internal UPS
and it's not going to have a consumer plug on it; GBe and better these
days.

I'll bet that a 10k RPM 200GB SATA disk ($200) would give faster
throughput than 200GB (at least $20,000) of ram at the end of a USB2
cable.

--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

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Zak <jute@zak.invalid> writes: 
>
> It means the manufacturer can sell it for a few years at most, then
> has to change the design and so on.

But that's true of just about any technology product.  This thing
should have no more complexity than a microcomputer memory board of
the CP/M era, which (unpopulated) cost a few hundred bucks, and those
things were made in fairly small quantity.

Or even simpler, is there such a thing as a PCI or AGP board with a
bunch of dimm slots?  I only know of the Giga-byte one, which has just
4 slots and 1gb/slot maximum.  Using a full length board should
accomodate 8 slots, and accomodating 2gb dimms would move the density
up to 16gb per board.  So with 4 of those boards in a 1U PC, that's
64gb per rack slot, which is getting somewhere.  Except for the 4GB
limit that board is almost exactly what I want, and it's just $50.

> Where do you buy cheap 2 or 4 GB dimms? Not a commodity product
> either. And it is not just sockets - it is drivers too. Running
> everything at lower speed may help. But again this needs research.

2GB is here at $120/GB:

http://www.zipzoomfly.com/jsp/Produ...oductCode=86040

4GB is still out of reach, but that will improve, and any boards being
designed today should be to accomodate them.

> Yes. And PC's are cheap compared to a custom design for a very narrow
> market.

Do you really think it's that narrow?  Fancy enterprise servers always
have large amounts of ram, and often do tasks that could be handled by
PC's with similar amounts of ram.  I'd think lots of people would want
this.
 
>
> There is (look up USB card reader). Then go and look at the speed and
> durability. And look at your ECC requirement again. It is cheap, yes.

Hmm, is there such a thing as a USB2 hub with 128 ports?  The ECC
could be handled with a RAID-like configuration.

Thanks.

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adykes@panix.com (Al Dykes) writes:
> I'll bet that a 10k RPM 200GB SATA disk ($200) would give faster
> throughput than 200GB (at least $20,000) of ram at the end of a USB2
> cable.

The problem is seek latency.  There are a lot of small requests with a
a completely random access pattern.

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Paul Rubin <http://phr.cx@NOSPAM.invalid> writes:
> Using a full length [PCI] board should
> accomodate 8 slots, and accomodating 2gb dimms would move the density
> up to 16gb per board.  So with 4 of those boards in a 1U PC, that's
> 64gb per rack slot, which is getting somewhere.

Bah, 1U cabinets usually can't accomodate multiple PCI cards, so it would
have to be 2U, still ok.

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I have a Toyota Corolla which I use for grocery store runs.  I'm
redoing my yard, and need to haul 10 tons of gravel home.  Can I just
add a few extra wheels on the side of the Corolla?  Bicycle wheels are
pretty cheap at the Salvation Army store, I can just buy two dozen of
them.  Since suspensions and axles are too expensive, I'll just
duct-tape them to the side of the Corolla.  But I need the reliability
of a high-end hauler, so I'll carry a spraycan of fix-a-flat with me.

Sorry Paul, but you are being completely unrealistic in your request.
You need to buy a Mack truck.  They are available at truck dealers
near you.  They are very very good at hauling gravel: efficient to
operate, very reliable, easy to use (once you've had the required
training).  But not cheap.

In article <7xbqum5d7l.fsf@ruckus.brouhaha.com>,
Paul Rubin  <http://phr.cx@NOSPAM.invalid> wrote:
>Zak <jute@zak.invalid> writes: 
>
>Just about anything--PCIe, Infiniband, heck, even USB2 or Firewire.

There is no market demand for very large RAM disk systems with
consumer (can you say "toy") interfaces, which have consumer speeds
and reliability.  People who need 500GB of RAM won't use a connection
that's designed for digital cameras; they will use something like
Fibre Channel or Infiniband.

>Is that a big deal?  What is so high tech about this?  It's just a
>bunch of dimm sockets on a board, right?

That's the easy part.  The hard part is the ECC, the memory
controller, the memory bus to interface controller (typically a
high-end CPU in and of itself), and the redundancy of the interface
controller.  You are talking about a big RAM-disk.  The easiest way to
acquire this is to buy a disk array with a lot of cache RAM.

Give me $50M, and I'll found a startup that will manufacture such
large RAM-disks with Infiniband interfaces.  You have to commit to buy
$200M worth of them per year from me though - because there seems to
be little other demand for them.

>  Giga-byte makes a PCI
>ramdisk with four dimm sockets for $50, but it can only take 1GB
>dimms.  I just want something like that but a lot bigger, maybe
>multiple boards, and able to use 2gb or 4gb dimms.  Let's say a 1U
>rack box containing a board with 32 or 64 dimm sockets.  A few of
>those with 2gb dimms (around $140/GB right now with ECC) and I'm
>there.

Find a motherboard with a two dozen PCI slots (which is nearly an
electrical impossibility, you will have multiple PCI busses at this
point, which is no longer a commodity PC).  If you want to use the RAM
as adressable core, you need a CPU with a huge address space, which is
not available on PCI slots.  This just can't be done with commodity
hardware.

>What PC's exist that can take more than 16GB?  I'd have to use dozens
>of them to get 500 GB of ram.

Go to HPs website, and look for whatever the Superdome is called now.
Look for an Itanium-based machine with 64 or 128 CPUs.  I bet that
thing can take 500 GB of RAM.  From a 50000' level, this thing is a PC
(it even boots Windows if I remember right) with quite a few CPUs and
a lot of memory, but with a single system image.  I'm sure you can get
equivalent offerings from IBM, Sun, and all the other usual suspects,
but those might be a little less PC-like, and more like Unix machines.
This is easily accomplished - but a little expensive.

>I also notice that flash memory in the form of SD cards is now around
>$25/GB in 4GB cards:
>
>  http://www.zipzoomfly.com/jsp/Produ...ctCode=82502-19
>
>I wonder if there's some way of sticking 128 or so of those in a box.

What's the speed of CF or SD?  You might wish for a spinning harddisk
instead.  Also, Flash memory (like SD and CF) can only be overwritten
so many times (the estimates range from 10K to 10M times); not
suitable for use like RAM.  And the reliability of such a device is
likely to be horrible.

There is a good reason we refer to these things as CRAP:
<C>ommodity-based, built from <R>eadily <A>vailable <P>arts.

I'm very sorry, you are trying to buy a Mack truck on a Corolla
budget.  Your best bet is the commercially available RAM disks (which
are frightfully expensive, because they serve a boutique-market).
Also carefully consider the following: if you can organize your
workload a little better to reduce seeks, and spread your workload
over a lot of spindles (disk drives), and you use very fast but
low-capacity disk drives, then disk drives might be your best bet.
For example, used 9, 18 or 36GB SCSI or FC disks, with 15K RPM (nice
Seagates), can be had used for not very much money today.  Those have
very very good seek times, much better than typical SATA disks.  If
you can stripe your workload over a hundred drives, and short-stroke
them (only the first few GB of each drive are used), you might be in
business.

Good luck!

--
The address in the header is invalid for obvious reasons. Please
reconstruct the address from the information below (look for _).
Ralph Becker-Szendy      _firstname_@lr_dot_los-gatos_dot_ca.us

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