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archer77

Member

Registered: 2015-04-16

Posts: 3

Truecrypt: Bad use of network bandwidth

Hi,

I have a VDSL25-connection which means an upload of 5,000 kbit/s. I'm writing to a remote truecrypt container, which lies on an SMB-share.

I only reach 1,100 kbit/s when writing via truecrypt. A direct write to the SMB-share results in a use of the full 5,000 kbit/s. So we can eliminate other causes except truecrypt.

I don't have any traffic shaper in place. System is up to date.

Any ideas what could be the cause? Many Thanks!

Alad

Wiki Admin/IRC Op

From: Bagelstan

Registered: 2014-05-04

Posts: 2,422

Website

Re: Truecrypt: Bad use of network bandwidth

I'm guessing because traffic is encrypted on the fly.

Last edited by Alad (2015-04-16 14:10:59)

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archer77

Member

Registered: 2015-04-16

Posts: 3

Re: Truecrypt: Bad use of network bandwidth

I'm guessing because traffic is encrypted on the fly.

Yes, it is encrypted on the fly. But my processor can do this faster than 1.000 kbit/s!

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: Truecrypt: Bad use of network bandwidth

Maybe because when you use truecrypt it is writing 512B or 4K at a time and when you do a direct write it will use larger chunks, thus being able to use all the available bandwidth. Mind you this is just a guess.

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R00KIE
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archer77

Member

Registered: 2015-04-16

Posts: 3

Re: Truecrypt: Bad use of network bandwidth

Maybe because when you use truecrypt it is writing 512B or 4K at a time and when you do a direct write it will use larger chunks, thus being able to use all the available bandwidth. Mind you this is just a guess.

Hi R00KIE,

I see your point. I did an iostat on the machine and wait time is nearly at 25% on the quad core machine.

Any ideas what's the cause? So CPU is waiting for the network (as network filesystem) but network is not used to capacity.

Regards archer

R00KIE

Forum Fellow

From: Between a computer and a chair

Registered: 2008-09-14

Posts: 4,734

Re: Truecrypt: Bad use of network bandwidth

That's beyond what I know so I can't be of much help there. The only things I can think of are trying a different filesystem if possible or tweak the one you are using to write larger chunks of data at a time.

My very big guess why this is happening is that it might be related to the bandwidth-delay product. I'll let the networking experts take over now, maybe someone already dealt with this before and knows what the problem is and any possible solutions.

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R00KIE
Tm90aGluZyB0byBzZWUgaGVyZSwgbW92ZSBhbG9uZy4K