Re: 8-15 TB storage: any recommendations?

[JohnS <jses27@xxxxxxxxx>]

On Fri, 2010-01-08 at 15:43 -0800, John R Pierce wrote:
> JohnS wrote:
> > Just asking is the fiber ports BiDirectional or Directional or can they
> > support a Bond that is BiDirectional of 4GB/s  or can they be trunked
> > into 16GB/s?  Bidirectional.   I need about 24 GB/s banwidth sustained,
> > yes per second.  Also what type of sparse file I/O you get .  I see you
> > stated multimode.  Some don't classify that as true BiDirectional
> > Bonding.
> >   
> 
> fiber is 4gbps (gigaBIT/sec) (or 1, 2, and now 8) and each FC link has 
> two fibers, either of which can be used to transmit OR recieve at a 
> given time (eg, each fiber is half duplex)..  MOST implementations use 
> one link to read and the other to write.   A 4gbps fiber can typically 
> sustain 400MByte/sec read or write, and potentially 400MByte/sec read 
> *and* write.
> 
> To hit 24GBYTE/sec, yeouch.   the IO busses on most servers don't have 
> that kind of bandwidth.    A PCI-Express 2.0 x16 (16 lane) card has 
> 8GB/sec peak burst rates.  The QPI bus on a Xeon 5500 server is around 
> 6GT/s peak for all IO including CPU->memory, if all transfers are 8 
> bytes (64 bits), thats 48GB/sec.

Ok what about the Dell R7** series on an i7. It's capable of at least
maybe 16gbits per second? That 16 maybe wrong though.

> BTW, in fiber, singlemode vs multimode refers to the optical modulation 
> on the fiber and has nothing directly to do with the duplex or 
> bonding.   single mode is more expensive, can transmit longer distances 
> (dozens of kilometers), while multimode is cheaper but only suitable for 
> relatively short distances (100s of meters).   Most all fiber channel 
> devices use replaceable SFP transceivers, so you can use either type of 
> transceiver with the appropriate fiber type.
> 
---
All that sounds correct.

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