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10:26:58
p_l
shka: now consider that some of those machines require 2x the memory vs. what you can use, due to RAIM in mirror mode
10:27:25
p_l
phoe: "on the street" is the pricing without "enterprise markup" (actually an extra guarantee among other things, important when dealing with that kind of money)
10:28:38
p_l
and if you deal with things like z-series mainframes you have a machine that has 2.5 the amount of memory you can maximally spec, because mirror RAIM and that .5 for internal use by machine itself
10:31:10
p_l
I heard anecdotes of a big z-Series losing whole I/O drawer under max load and it having not affected the application
10:33:47
flip214
well, we've got a customer who didn't notice that his RAID controller was dead for two weeks, because the data was accessible via the software-mirror (DRBD)
10:35:23
p_l
flip214: this is more a case where the I/O of the system, which was under load (including things like mirroring to another machine) was unaffected
10:36:06
p_l
IO drawer is where things like Ethernet, Infiniband and FC (plus occassional ancient ESCOM) cards sti
10:37:31
p_l
reliable in-memory systems tend to be expensive as well, especially when you don't want to directly deal with disk (either huge expensive NUMA systems, or RDMA)
10:53:52
shka
p_l: RDMA is getting cheaper, and besides, even without RDMA you can build reasonable system
10:56:16
p_l
shka: yes, but the latencies make it very far from "let's just think of memory instead of multiple completely disparate systems"
10:57:00
p_l
and in my experience, companies balk when I suggest "ok, let me hit ebay, I'll have the 56GBit low-latency fabric ordered by tomorrow on the cheap" ;)
10:59:19
shka
anyway, those would be different beast, i agree, but this approach has some advantage over ultra expensive huge IO mainframes
10:59:56
p_l
most companies that lease mainframes have very specific reasons for doing so (combination of RAS requirements, power, software base, etc.)
11:01:05
flip214
you can get 56gbit IB, 2 dual-port adapters and 2 cables (so two machines can talk 112gbps) for < €1000
11:03:05
flip214
so all of the data needs to have been seen before the first data byte can be transmitted
11:04:25
p_l
shka: there are some low-level details that impact how fast you can go with Ethernet without changing it into non-Ethernet, including how it's designed for Store-and-Forward data
11:05:25
p_l
shka: IB doesn't have store-and-forward inside subnet (most sites anyone sees are single subnet)
11:08:17
p_l
Netherlands used Myrinet on mixed Myrinet/10GbE links, in poland I think we did something shitty with plain IP... ;)
11:08:45
p_l
flip214: IB uses IPv6 *addressing*, and intra-subnet packets have 16bit address for wormhole routing
11:09:32
p_l
the 16bit addresses are internal affair of the subnet that software stack is not supposed to bother itself with (outside of management software for subnet itself)
11:11:54
p_l
it's much harder to do wormhole switching when you have to match complex 128bit addressing to ports ;)
19:27:33
rpg
I suspect that CL-DOT cannot handle subgraphs, but I'm not 100% sure. Can anyone confirm?
21:29:51
fiddlerwoaroof
When I quickload it in Lispworks, I get an error about defining (METHOD DESCRIBE-OBJECT :AFTER (SYMBOL T)) visible from package Common-Lisp
21:31:13
fiddlerwoaroof
I guess this settles it: "Users can write methods for describe-object for _their own_ classes if they do not wish to inherit an implementation-supplied method."
21:32:52
aeth
I would guess that quite a lot of things do not run in LispWorks. e.g. I try to test in everything but clisp (too many missing non-standard features) and the proprietary Lisps. And things frequently have broken in subtle ways by the next time I test in CCL, ECL, etc.
21:33:43
aeth
e.g. Once there was an issue with the way I coerced some numbers between numeric types that only showed up in CCL iirc.
21:35:31
aeth
Anything large and complicated enough has a good chance to not run in a random CL without testing finding some minor things that the other CLs tolerate.
21:39:10
fiddlerwoaroof
I've found that usually it works just fine and, when it breaks, the fix is fairly simple
21:39:44
aeth
There are a lot of things that aren't in the standard but are de facto standard, and an implementation not complying can cause pain. e.g. CLISP has a 64-bit fixnum that's far too small, and doesn't have double-float or single-float specialized arrays.
21:40:05
aeth
So a library that assumes single-float specialized arrays and assumes that the Lisp will have them and type check and error if the type is wrong will not work as intended on CLISP.
21:41:45
fiddlerwoaroof
Yeah, but this isn't really a question of unspecified behavior: the standard doesn't allow users to defmethod DESCRIBE-OBJECT on standard classes.
21:44:35
aeth
My example was bad... Looks like ECL doesn't type error like SBCL and CCL or just put the double there (because it's a T array) like in CLISP.
21:51:14
aeth
fiddlerwoaroof: Well, a similar issue pops up, then. Sometimes only one implementation follows the standard correctly, and the bug is only spotted because the code tries to be portable.