why am I getting old WU's?

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Profile Martin A. Boegelund
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Message 166707 - Posted: 12 Sep 2005, 10:57:15 UTC - in response to Message 166704.  


If you think of the cosmos as being millions of years old, and seeing stars that are thousands of light years away, and sound tranvels slower than light, the signals when we finally hear could be very old. So, what is the difference if we find it in 1999 tapes, or 2006 tapes? Plus how much longer after it is found will it take us to translate it, or figure out where it came? What if that civilization has already died off, when we finally hear it?

Just a few thoughts to ponder.



They aren't that far away. They are waiting in their mothership behind the moon!
Haven't you seen the movie "Independence Day"?

:p
"Are you suggesting coconuts migrate?"

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Message 166745 - Posted: 12 Sep 2005, 12:56:28 UTC - in response to Message 166707.  

They aren't that far away. They are waiting in their mothership behind the moon!
Haven't you seen the movie "Independence Day"?:p


They'll have to wait in line after the Invaders from Mars. Although they might attack us from the other direction.
No animals were harmed in the making of the above post... much.
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Message 166746 - Posted: 12 Sep 2005, 12:57:48 UTC - in response to Message 166745.  

They aren't that far away. They are waiting in their mothership behind the moon!
Haven't you seen the movie "Independence Day"?:p


They'll have to wait in line after the Invaders from Mars. Although they might attack us from the other direction.


Maybe they will discover each other, think of each other as a threat, and leave us alone (-:



My movie https://vimeo.com/manage/videos/502242
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Message 167038 - Posted: 13 Sep 2005, 3:15:59 UTC - in response to Message 166704.  

If you think of the cosmos as being millions of years old, and seeing stars that are thousands of light years away, and sound tranvels slower than light, the signals when we finally hear could be very old.

The signals that SETI is looking at are electomagnetic waves (radio signals). These travel at the speed of light, not the speed of sound. Besides, sound does not travel in a vacuum as there are no air particles to move to transmit the sound. Yes, the signals will probably have been sent long ago when we get them.


BOINC WIKI
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Profile Martin A. Boegelund
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Message 167165 - Posted: 13 Sep 2005, 12:51:38 UTC - in response to Message 166746.  

They aren't that far away. They are waiting in their mothership behind the moon!
Haven't you seen the movie "Independence Day"?:p


They'll have to wait in line after the Invaders from Mars. Although they might attack us from the other direction.


Maybe they will discover each other, think of each other as a threat, and leave us alone (-:



Woow! That could make a great movie plot!

"Are you suggesting coconuts migrate?"

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Profile Martin A. Boegelund
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Message 167166 - Posted: 13 Sep 2005, 13:04:46 UTC - in response to Message 167038.  

If you think of the cosmos as being millions of years old, and seeing stars that are thousands of light years away, and sound tranvels slower than light, the signals when we finally hear could be very old.

The signals that SETI is looking at are electomagnetic waves (radio signals). These travel at the speed of light, not the speed of sound. Besides, sound does not travel in a vacuum as there are no air particles to move to transmit the sound. Yes, the signals will probably have been sent long ago when we get them.


...which completes the round trip by taking us back to earnestness. Thank you for the explanation.

Grooks by Piet Hein:
THE ETERNAL TWINS

Taking fun
as simply fun
and earnestness
in earnest
shows how thoroughly
thou none
of the two
discernest.

"Are you suggesting coconuts migrate?"

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Message 167194 - Posted: 13 Sep 2005, 15:11:03 UTC - in response to Message 167038.  

If you think of the cosmos as being millions of years old, and seeing stars that are thousands of light years away, and sound tranvels slower than light, the signals when we finally hear could be very old.

The signals that SETI is looking at are electomagnetic waves (radio signals). These travel at the speed of light, not the speed of sound. Besides, sound does not travel in a vacuum as there are no air particles to move to transmit the sound. Yes, the signals will probably have been sent long ago when we get them.


This isn't strictly true, but it is close enough to true for most practical purposes. The solar wind does propagate shockwaves; these shockwaves travel faster than "sound" would in this extremely thin medium, and all of the predicted fluid dynamics work out (the shockwaves produce "sonic booms" that perturb the solar wind, etc.).

Sound does not travel in a vacuum, but interplanetary space is not a true vacuum. Of course, the fluid density is so vanishingly small that there is nothing that anyone would describe as "sound" out there.

Your main point is still the main issue: SETI@home is looking for radio signals. They will most likely be very old when we receive them.
No animals were harmed in the making of the above post... much.
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Message 167223 - Posted: 13 Sep 2005, 16:48:24 UTC - in response to Message 165832.  

What are the dimensions of a 1-5TB drive? Chances of picking it first? Should we start a thread for this?


the dimensions aren't that big physicly (if one is happy with SATA drives, SCSI needs more drives). got 8x250GB on my sata raid in my big tower box here (2x250gb mirrored for system/progs - 250gb usable, 6x250gb raid5 for data - usable 1.13tb)
if you consider that e.g. adaptec has a 16 port sata raid controller and you don't waste space for splitting system/data, you could do a 16x400gb storage server (raid5 would result in 6tb - space lost for file system).

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Message 167304 - Posted: 13 Sep 2005, 21:19:05 UTC - in response to Message 167223.  

if you consider that e.g. adaptec has a 16 port sata raid controller and you don't waste space for splitting system/data, you could do a 16x400gb storage server (raid5 would result in 6tb - space lost for file system).

YEs, but, RAID-5 is slower than a mirror. So, with speed being one of the probable problems, it is not used on heavly loaded disks.
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Message 167443 - Posted: 14 Sep 2005, 1:34:54 UTC - in response to Message 167304.  

if you consider that e.g. adaptec has a 16 port sata raid controller and you don't waste space for splitting system/data, you could do a 16x400gb storage server (raid5 would result in 6tb - space lost for file system).

YEs, but, RAID-5 is slower than a mirror. So, with speed being one of the probable problems, it is not used on heavly loaded disks.


more noticable on writing, not much impact on reading. having a hardware controller that calculates the XORs, i am not sure how big the impact on writing is (considering the controller has a decent dimensioned cache)... will google on some hdd benchmark tools and measure it later ;)

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Message 167482 - Posted: 14 Sep 2005, 2:55:13 UTC - in response to Message 165643.  

You know? I've reread this and maybe Orgil is trying to say he/she thinks it would be better if WU were done in chronological order, rather than in a random fashion.

No, Orgil thinks that he is being denied "newer" work units and only getting sent older ones. It seems to him to be a conspiracy of some sort.
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Message 167501 - Posted: 14 Sep 2005, 3:36:43 UTC - in response to Message 167304.  

if you consider that e.g. adaptec has a 16 port sata raid controller and you don't waste space for splitting system/data, you could do a 16x400gb storage server (raid5 would result in 6tb - space lost for file system).

YEs, but, RAID-5 is slower than a mirror. So, with speed being one of the probable problems, it is not used on heavly loaded disks.

It appears (reading between the lines) is that the speed problem was more about caching directories than actual read/write performance.

From that it makes me think that it isn't disk size (storage) that is an issue as much as directory size.

... and splitting the file system seems to have proven that.
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Message 167529 - Posted: 14 Sep 2005, 5:38:46 UTC - in response to Message 167304.  

if you consider that e.g. adaptec has a 16 port sata raid controller and you don't waste space for splitting system/data, you could do a 16x400gb storage server (raid5 would result in 6tb - space lost for file system).

YEs, but, RAID-5 is slower than a mirror. So, with speed being one of the probable problems, it is not used on heavly loaded disks.


Most, if not all, of the SATA controllers I have looked at also provide RAID modes 0 and 1, and can be combined to provide RAID 01, so that speed and security of data is not really a problem. Admitted SATA is still not quite as fast as SCSI but it is about half the price, and can be fairly fast, WD Raptor dives, or larger, Hitachi now offers 500 GByte drives.

Andy
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Message boards : Number crunching : why am I getting old WU's?


 
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