How can I stop LTSPice from using the hard drive

[Joerg]

Hello Joerg,
I just run a simulation with LTspice generating a 100MB raw-file.
The simulatiomn tooks 90sec and I saw the hard disk lamp blinking about 140
times.
That's by far not any stress for a harddisk.

I'll live with it for now. If I move the *asc. files to the PC before
simulating at least it grinds on the PC disk, not on the LAN server.
Thing is, I do a lot of other stuff on this PC when simulations run.

LTspice uses internal caches to keep the waveform data.
You can look traces in a 100MByte raw-file with terriffic speed.
That's only possible because LTspice keeps most data in RAM too
as long as you don't run out of RAM.

But then why doesn't it keep that whole 100MB raw data file all in RAM?
I am sure your PC has 2GB or more like mine.

 

[Helmut Sennewald]

I'll live with it for now. If I move the *asc. files to the PC before
simulating at least it grinds on the PC disk, not on the LAN server. Thing
is, I do a lot of other stuff on this PC when simulations run.



But then why doesn't it keep that whole 100MB raw data file all in RAM? I
am sure your PC has 2GB or more like mine.

Hello Joerg,

I recommend you to send an email to Mike and ask for the feature
of a RAM only raw-file.
It's email address is in the Help->About of the LTspice program.

Best regards,
Helmut

 

[Joerg]

Nothing found with that number with Google or on the WDC search page.


What model SMC? Sorry to be so obnoxious about extracting the exact
model number out of you, but it does make a difference. For example,
if the "SMC" were a dual speed hub instead of switch, you will have
performance (and reliability) problems.

SMC 7008 BR. It never had any performance or reliability issues. Jim
Thompson's SMC died a slow death, needed frequent resets, but not mine.
It may not fulfill the needs of a high data volume user but is perfectly
adequate for what I need it to do.

Yeah, building temp files over the LAN is not a great idea. If your
PC is capable of doing gigabit, you might consider replacing your
"SMC" with a suitable 10/100/1000 switch. I'm surprised that you
claim that you don't need the speed. I run backups from the server to
DVD and find myself waiting for the network, even with gigabit. Fast
is fun, especially when gigabit switches are very cheap.

Well, I run backups and stuff during lunch and dinner time. Or I just
let it trundle on in the background, there you don't even feel it.

No videos, photos, games, archived applications, disk images, CD and
DVD images, mirrored web sites, and image backups? My data dumpster
if full of this kind of stuff. Sure, your minimal applications don't
require much horsepower, but they're certainly no fun.

I use the PC only as a tool. Just like pliers, wrenches and stuff. Fun
for us is splashing in the pool, hiking, playing games, the pool table,
going out for dinner, those kinds of things

Good, fast, cheap... pick two.
You bought good and cheap, (I beg to differ about good, but perception
is everything), and missed on the fast. I've never lost a customer
because it wasn't cheap. I've heard some initial grumbling if it
wasn't fast. However, if it's not good, I'm history. For mission
critical applications and picky customers, I use two NAS boxes
replicating each other with a 1 day or more delay (to allow recovery
of accidentally erased files and to recover from update disasters).
Backups are disk image files, so I don't miss anything, no matter how
minor.

Let's put it that way, good and cheap is good enough for me and my
business

It should work (famous last words).

Last words in the west: "Hey y'all, watch this now!"

 

[Joerg]

Hello Joerg,

I recommend you to send an email to Mike and ask for the feature
of a RAM only raw-file.
It's email address is in the Help->About of the LTspice program.

Good idea, I'll do that. But I don't want to sound like a complainer.
LTSpice is a free program and quite frankly the most excellent SPICE
simulator I have ever used. There is such a thing as a free lunch

 

[JosephKK]

This reflects the fact that Windows uses a *huge* disk cache by default
(hundreds of megabytes if no other program requests the memory!), and the
folks at Microsoft seemed to equate using a RAM disk to "I want really fast
performance" (as opposed to Joerg's "I don't want my mechanical hard drive
grinding"), which a huge cache provides, so this is why they make you go to
some effort to get a "real" RAM disk.

Or at least that's my interpretation of events.

This brings up an interesting alternative. I used to be able to
disable disk swap space entirely for a few restarts. It may still be
possible. Better not have anything else running at the same time
though.

 

[JosephKK]

Ok, bad guess and bad design. Temp files should stay local.


I have a working directory on 4 of my local machines (2 of which are
laptops). The local documents, client, and working projects are setup
to replicate to the file server, data dumpster, and backup device. I
use Windoze Briefcase for the Windows boxes and rdist for the Linux
stuff. All are automatic or cron based. The trick is that I never
edit the files directly on the file server. Edits are always done
locally. Synchronization is always one way, from the local machine,
to the file server, never the other direction. Of course, I'm very
careful to maintain accurate date and time information. While there
was a major learning exercise many years ago, it hasn't failed for
maybe 8 years.


Any particular model number WD NAS box? I think you'll find that your
WD box does NOT cache writes. I need he model number to be sure. Last
time I ran IOZONE on some NAS boxes, it was apparent that there was
plenty of read cache, but writes went straight to the drive. Look on:
<http://www.smallnetbuilder.com/content/view/85/93/>
for NAS benchmarks and tests on your WD. If you feel ambitious,
compare the results with a "real" server, which uses main memory for
caching both reads and writes. I've replaced several NAS boxes with
Linux servers that simply couldn't keep up with the load (mostly brain
dead applications that scribble all over the server, open huge number
of files, do numerous sync operations for no obvious reason, etc.


Dunno. I was doing SPICE in college in the last 1960's.

My guess is that someone didn't test the hell out of every possible
network configuration or goofed by forcing a temp file to live across
the network.


It could, but how old Switcher CAD (LT Spice)? Probably as old as
Linear Tech which was founded in 1981. As I recall, the IBM PC
arrived in the same year.

No such luck. Spice that would run on a PC is only since 1985
(Intusoft) and the help->about for LTSpice only goes back to 1998.