It’s a reasonable limitation stated
by NetApp after thoroughly testing the overall throughput capabilities of a
fibre channel interface. They found
that on busy systems, with a reasonably distributed I/O (WAFL) mix, the FC-AL will
become saturated or incurred extended wait states as more disks are added to
the FC. They picked an even interval,
based on shelf size, closest to the maximums. They also addressed reliability and
processor performance concerns. Too many disks on one link will increase
the probability of a single point of failure. On NetApp’s larger systems separate
fast PCI busses support multiple FC interfaces. This architecture and set limitation assures
that disks don’t have wait on a FC and FC interfaces, running at max
speed, don’t end up waiting PCI buss throughput. As FC, disk transfer speeds and buss
architectures change these recommended limits (54) may change again too.
Hunter
.
Hunter M. Wylie
Bus: 503-633-8900
FAX: 503-633-8901
Cell: 503-880-1947
http://www.itmls.com/
-----Original Message-----
From: owner-toasters@mathworks.com
[mailto:owner-toasters@mathworks.com] On
Behalf Of Waters, G Scott (DSTI)
Sent: Friday, April 25, 2003 12:09
PM
To: 'Clawson, Simon';
jeff.mery@ni.com; toasters@mathworks.com
Subject: RE: FC9 & DS14 on
same FC-AL adapter...
I am curious about the 56 disk rule. To what does it
apply. I ask that because I currently have a filer with 63 disk in one
loop and no *known* problems.
Please enlighten me.
Thanks.
- Scott W.
-----Original Message-----
From: Clawson, Simon [mailto:simon_clawson@mentorg.com]
Sent: Wednesday, April 16, 2003 11:26 AM
To: 'jeff.mery@ni.com'; toasters@mathworks.com
Subject: RE: FC9 & DS14 on same FC-AL adapter...Yes. We have FC7, FC9 and DS14 on the same loop.
The rules are - the shelves must be linked in order of oldest to newest - FC7 -> FC9 -> DS14. You cannot have more than 56 disks on one loop.
Simon
-----Original Message-----
From: jeff.mery@ni.com [mailto:jeff.mery@ni.com]
Sent: 16 April 2003 16:16
To: toasters@mathworks.com
Subject: FC9 & DS14 on same FC-AL adapter...
Fellow Toasters,
Does anyone know if FC9 and DS14 shelves can co-exist on the same FC-AL adapter? If so, are there any special rules that must be followed (i.e. DS14s at beginning/end/certain shelf IDs etc.)?
Thanks in advance,
Jeff Mery, MCP
National Instruments
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