On Fri, 28 Apr 2006 02:20:02 -0600
Andreas Dilger <[EMAIL PROTECTED]> wrote:

> I don't know why people are so keen on ECC RAM.  Why not just put an
> extra socket on the board and run the RAM in "RAIM" (RAID for Memory)
> mode? The incremental cost of ECC vs. regular RAM is FAR more than
> the cost of just getting the extra stick of RAM.  Also, with RAIM you
> could even hot-swap a failing DIMM, while with ECC you have to take
> an outage to get back to redundancy.

If I remember correctly, old Alphas used this method - 5 slots per memory bank.

> Ah, but if you can connect the RAM to multiple machines, you could at
> least have the hope of hot failover for the storage to another server.
> That isn't something you can do with a bus-attached device.

SATA doesn't allow you to connect a device to multiple machines (at least not 
yet, who knows what SAS will bring in the future). If you want to have SSD with 
ability to hang multiple machines on it, you have to look for fibre channel 
models which are waay to expensive.
 
> Even the chance of any recovery is far better with such a setup (i.e.
> plug into another system after motherboard dies), since you can at
> least get access from another machine.

Another example of "ram with battery" are umem cards, which are very difficult 
to obtain. But they do work at pci bus speeds. Linux supportd 5415 and 5425 
models. I managed to get a 5420 model, which looks like it was made 
specifficaly for Sun and doesn't work with the existing driver. I'm hacking it 
in my spare time and I hope I can get it working...

-- 

Jure Pečar
http://jure.pecar.org

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