Re: formula for calculating the max number of disks on a loop without losing performance

supported (see config guide on NOW): are 4 ds14 shelves (with lrc) on 1 loop. are 6 ds14 shelves (with esh) on 1 loop.

imho performance will increase if you add 1 fc-hba to each node and dual attach the shelves with esh-modules.

Derek Lai wrote:

We currently have a FAS940C cluster. Each of the FAS940 has 2 DS14 shelves of 36 GB drives and 1 DS14 shelf of 72 GB drives (a total of 6 shelves). Each of the FAS940 has only 1 FC dual-channel Host Adapter:

    slot 4: FC Host Adapter 4a (Dual-channel, QLogic 2312 rev. 2,

64-bit, L-port, <UP>)

We are trying to isolate some performance problem we are encourtering. How do we find out if the host adapter is the bottleneck? Does anyone have a formula for calculating how many drives can be put on a single loop without losing performance. Thanks.

Derek