On Thu, Mar 09, 2000 at 12:44:32AM +0100, Jakob �stergaard wrote:
>
> You don't _think_ you would see better performance ?
>
> I'm pretty sure you will see better performance. But on the other
> hand, with a large number of disks, sometimes the hot-swap
> capability comes in handy, and sometimes it's just nice to have a
> red light flashing next to the disk that died. Hardware RAID
> certainly still has it's niche :) - it's just usually not the
> performance one.
>
If there isn't hot-swap RAID 5 with auto rebuild, it will never
happen.
Let me give you an idea of the scale we are trying to ramp Linux up
to. The project I am on right now is to determine whether Linux is
capable of matching the performance and scalability of the commercial
Unices for the ASCI (Accelerated Strategic Computing Initiative)
project. I have a small 32 CPU, 8 node cluster of Alphas with which
to do development and testing on. What we are doing on that system is
porting the device driver for the Elan interconnect, porting MPI over
that interconnect, porting a suite of clustering tools including a
GANG scheduler and resource manager, and equipping it with RAID 5 and
a global file system. This will all be done on the small cluster with
testing and benchmarking and all the trimmings. Now, assuming we can
reach a reasonable performance level on this (I'm confident we will at
least match True64), then we will look at building a much larger
system with >= 128 nodes.
The big brother of our little cluster sits in the same machine room as
ours. It is serial number 1 for Compaq's Sierra class cluster and
comprises 128 ES40 (same as our little cluster) and runs True64. A
couple of weeks ago, the storage systems arrived on about ten palettes
in the machine room. This is a 12 terabyte RAID 5 storage system
comprising several of Compaq's StorageWorks enclosures using Fibre
Channel as the transport.
This is the sort of thing we are hoping to put into production using
Linux. The reason for this is it is much easier for us to port and
maintain software across various platforms without having to switch
operating systems every time a different vendor wins a bid to deliver
a new computer. I think IBM will come around and if we are successful
in this project, we will probably be able to bully Compaq into
supporting Linux on such a grand scale as well. SGI is already
betting the farm on it.
>
> Ok, please try both SW and HW setup when you get the chance. This is a
> situation that calls for real numbers.
>
As soon as the new equipment gets installed (scheduled for tomorrow),
I'll see if I can get a kernel compiled up on one of my nodes for
software RAID 5 and plug in one of the storage cabinets to it. I need
to start producing real numbers now so that I can present a case to
the parties involved to make some changes to how things are being
done.
BAPper
