Re: Load balancing across multiple network paths

On Wed, 2004-12-08 at 12:32, Peter T. Breuer wrote: 
> As aliases? You mean two addresses on the command line, one per (slave)
> daemon? Can't say that I've tried that for a while ...

Yes, I start the client with

enbd-client 192.168.0.1:12345 192.168.0.1 192.168.1.1 -b 4096 /dev/nda

> > notice that both network interfaces are being used (confirmed also in
> > /proc/nbdinfo stats)
> 
> How does it show that, exactly? Can you post the stats maybe?

Doing a 
dd if=/dev/nda of=/dev/null bs=64k count=4k
just after starting the client gives the following /proc/nbdinfo

Device a:       Open
[a] State:      verify, rw, merge requests, enabled, show_errs, last
error 0, lives 0, bp 0
[a] Queued:     +0R/0W curr (check 0R/0W) +1R/1W max
[a] Buffersize: 262144  (sectors=512, blocks=64)
[a] Blocksize:  4096    (log=12)
[a] Size:       16811008KB
[a] Blocks:     4202752
[a] Sockets:    2       (*)     (+)
[a] Requested:  64.056K (35.4K) (28.6K) 64.05KR/0W      max 32
[a] Despatched: 64.056K (35.4K) (28.6K) 64.05KR/0W      md5 0W (0 eq, 0
ne, 0 dn)
[a] Errored:    0       (0)     (0)     0+0
[a] Pending:    0       (0)     (0)     0R/0W+0R/0W
[a] B/s now:    0       (0R+0W)
[a] B/s ave:    1.54M   (1.54MR+0W)
[a] B/s max:    8.14M   (8.14MR+0W)
[a] Spectrum:   99%32
[a] Kthreads:   0       (0 waiting/0 running/1 max)
[a] Cthreads:   2       (+)     (+)
[a] Cpids:      2       (811)   (812)
Device b-p:     Closed

Firstly, the B/s max is close to the theoretical max of a 100Mbit/s NIC
(isn't it?). Second, the Requested and Dispatched are not the same, but
not that far from each other, which would mean that both daemons are
doing work, no?

> > but in alternation, not in parallel. The result is
> > that the total throughput ends up being the same as that of a single
> > NIC's.
> > 
> > Is that normal? According to the man page of the client, the throughput
> > should increase proportionally to the different network routes. Any
> > ideas?
> 
> The daemons are independent. They do not alternate, because they do not
> (in effect) know the other exists. So there is some other explanation.

So, from what you saying I should expect almost double throughput? Hm,
curious...

Nikos



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