[CentOS] 8-15 TB storage: any recommendations?
jses27 at gmail.com
Sat Jan 9 00:27:37 UTC 2010
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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