Hi all, I can't seem to find much about this on the forums, so I thought I'd ask.

I'm looking to build a dedicated PC for SETI, and was wondering how important hard drive speed really is to the whole process. I know that BOINC caches some files to the drive, but if I put a slower drive in there (like, say, something as slow as a CF card), will I notice any difference in speed?

Not much really. The hard drive is the least important aspect of the entire chain of performance as it relates to the SETI app. The most important is the CPU, then the L2 cache, then the RAM, then the hard drive.

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Hi all, I can't seem to find much about this on the forums, so I thought I'd ask.

I'm looking to build a dedicated PC for SETI, and was wondering how important hard drive speed really is to the whole process. I know that BOINC caches some files to the drive, but if I put a slower drive in there (like, say, something as slow as a CF card), will I notice any difference in speed?

As far as the actual processing of tasks the time is, as OzzFan says, is swamped by other factors. However, you will notice that the system as a whole will be more and more sluggish as the drive speed goes down.

FYI I have had drives from 5,400 to 15K in my systems and the run time of the tasks did not show any eyeball detectable difference. I am sure were I to have done a data search I could have found a difference, but it would likely have been in the seconds area for tasks that ran for more than a day ... minutes for those over a week and possibly as much as an hour for those that ran for several months.

Measurable, but hardly a killer.

I would only add a couple notes to his stream where CPU architecture and clock speed (newer architecture and faster speeds = better), L1, L2, and L3 cache size (speed is usually tied to system clock speed and is not independently controllable), RAM interleave (single channel, dual channel, tri-channel, etc. then architecture DDR2 vs DDR3 etc., then RAM speed), MB chipset and quality, then hard drive (bus speed/type then rotational speed, 5,400 worst, 7,200 good, 10K better, 15K best, but also hottest and most expensive)... Oh, and HDD cache is the same as CPU cache, bigger is better, but after 16M is not likely to show much difference ...

Then we have the GPU ... :)

If the computer is going to be a cruncher box you rarely need a drive bigger than 30-60G so you can trade size for higher speed. I got a 10K on sale for what a "normal" size 7,200 RPM drive would have cost ... still have 34G Free out of 40G HDD installed...

Of course I have my data files on a 2.38TB raid array so if you use the machine for other work, YMMV ...

Ok, thanks for the responses! I'm mainly interested in ways to keep power consumption down (as down as a 24/7 cruncher can be, of course), and was toying with the idea of using a CF card or a USB stick as the hard drive because they have lower power draws.

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Ok, thanks for the responses! I'm mainly interested in ways to keep power consumption down (as down as a 24/7 cruncher can be, of course), and was toying with the idea of using a CF card or a USB stick as the hard drive because they have lower power draws.

Very good summary from Paul there. And a good idea on going "diskless".

Best would be to get additional system RAM to max out whatever your motherboard (mainboard) can take (RAM is cheap!) and then use a RAM disk. Then set a scheduled task to copy the RAMdisk over to a USB memory stick say twice a day or so as a backup against power failure or Windows BSODs.

But then again... USB memory sticks are cheap enough and will last long enough (writes wear levelling) that they can almost be considered 'disposable'...

Do whichever you feel is the better, more interesting, or easier, whichever you wish.

(USB memory sticks have a limited number of writes, near infinte reads, and s@h writes state information out to disk every few seconds. Hence you can expect a USB memory stick to fail after a few months or so continuous use with s@h. Hence the RAMdisk idea to reduce USB memory wear.)


Happy fast crunchin',
Martin

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Ok, thanks for the responses! I'm mainly interested in ways to keep power consumption down (as down as a 24/7 cruncher can be, of course), and was toying with the idea of using a CF card or a USB stick as the hard drive because they have lower power draws.

If, for example, you add CUDA ... the draw of the disk drive is not even going to be noticeable ...

Ok, thanks for the responses! I'm mainly interested in ways to keep power consumption down (as down as a 24/7 cruncher can be, of course), and was toying with the idea of using a CF card or a USB stick as the hard drive because they have lower power draws.

If you have enough RAM (so that the necessary parts of the OS all fit in RAM), including BOINC and the science application and data, then disk speed will be almost completely unimportant.

That said, a modern, fast (7200 rpm), 2.5" laptop SATA drive draws 3 watts or less. I haven't compared that to modern 3.5" drives, but I wouldn't be surprised to see that they're under 8 watts or so.

If you really want to save power, look to the CPU. If the CPU is using 90 watts, shaving a few watts off the hard drive consumption won't matter.

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If it's a dedicated crunching box then any old disk thats big enough to hold the OS and work units will do the job fine. An old recycled 20gb from the spare parts box will work OK. The machine will take a few more seconds to boot and load big programs, but once it's running and crunching the disk has practically no effect.

An old 5400 rpm disk probably only draws 5 watts idling, compared to the 50-100 watts the CPU is sucking, it's nothing.

Extra ram also has little effect in a dedicated cruncher, as long as you have enough for the OS and Boinc tasks, then more doesn't help a lot. A normal PC, yes extra ram is good, on a dedicated cruncher, it's just not used for anything. Running the RAM as dual channel will give a small inprovement, so thats a good idea.

Graphics card, unless you are running CUDA, get a low power graphics card or use an integrated graphics chip. Using the onboard chip will use less power, but decrease performance sligthly. A dedicated card, a little more power, but no memory contention issues should increase performance a little. Even an old 2mb PCI graphics card would work, low power and moves the graphics ram off the system board.

But the CPU choice is the main thing, both for performance and power use. Everything else is just needed to keep the CPU running. So you can save $$ and power, and put that into a better CPU and you will get more bang for your buck.

Ian

I would only add a couple notes to his stream ...

LOL I was actually going to type all that up - and indeed I did have it in the message box, but then I decided to keep it simple. Perhaps I should stay with my pedantic tendencies so that I keep accurate for everyone! :)

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I would only add a couple notes to his stream ...

LOL I was actually going to type all that up - and indeed I did have it in the message box, but then I decided to keep it simple. Perhaps I should stay with my pedantic tendencies so that I keep accurate for everyone! :)

Pedant, thats me ... :)

Plus the teacher bone ... or maybe bone head?

Anyway, when you are home and alone except for the two dogs and three GPU cards ... well, one starts to talk to the computer ... then you start to type too much ... and it is all downhill from there ...

I would only add a couple notes to his stream ...

LOL I was actually going to type all that up - and indeed I did have it in the message box, but then I decided to keep it simple. Perhaps I should stay with my pedantic tendencies so that I keep accurate for everyone! :)

Pedant, thats me ... :)

Plus the teacher bone ... or maybe bone head?

Anyway, when you are home and alone except for the two dogs and three GPU cards ... well, one starts to talk to the computer ... then you start to type too much ... and it is all downhill from there ...

You are in trouble when you start having conversations with the computer.

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BOINC WIKI

You are in trouble when you start having conversations with the computer.

No, trouble is on the horizon when you start having arguments with the computers.

You are in trouble when you start to lose those arguments.

You are in trouble when you start having conversations with the computer.

No, trouble is on the horizon when you start having arguments with the computers.

You are in trouble when you start to lose those arguments.

Or your computer is speech-driven, like these data-driven forum pages. ;^)

Just joking, though.

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Ok, thanks for the responses! I'm mainly interested in ways to keep power consumption down (as down as a 24/7 cruncher can be, of course), and was toying with the idea of using a CF card or a USB stick as the hard drive because they have lower power draws.

Very good summary from Paul there. And a good idea on going "diskless".

Best would be to get additional system RAM to max out whatever your motherboard (mainboard) can take (RAM is cheap!) and then use a RAM disk. Then set a scheduled task to copy the RAMdisk over to a USB memory stick say twice a day or so as a backup against power failure or Windows BSODs.

But then again... USB memory sticks are cheap enough and will last long enough (writes wear levelling) that they can almost be considered 'disposable'...

Do whichever you feel is the better, more interesting, or easier, whichever you wish.

(USB memory sticks have a limited number of writes, near infinte reads, and s@h writes state information out to disk every few seconds. Hence you can expect a USB memory stick to fail after a few months or so continuous use with s@h. Hence the RAMdisk idea to reduce USB memory wear.)


Happy fast crunchin',
Martin

You can also adjust the 'write to disk every X seconds' parameter in the BOINC client, although AFAIK this affects the SETI client and not the BOINC daemon which writes its client state to disk fairly often.

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Ok, thanks for everyone's input. I'm going to try running the computer off of a 4GB flash drive for now, mainly because the spare hard drives I have are whiny and loud. Hopefully this will quiet it all up a bit, and save a little on power at the same time.

I'll post again if the drive dies in the next few months, but I hope it lasts at least a year to justify the cost and effort!

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