Hashrate drops immediately preceding diff rises?

[woodrake]

I've noticed that lately network hashrate drops briefly by ~10% (or more) just before a difficulty retarget. The most recent example of this was (yesterday) was about 100 TH/s.

Does this suggest that some of the large players are deliberately taking their estate offline in order to try and keep difficulty lower than it would otherwise be?

This would strategy would require that difficulty is calculated by the spot network hashrate at the changeover time - is that the case or is it based on a recent average?

Kate.

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[gmaxwell]

You didn't mention how you're measuring this. Pieter's dont seem to show that, and estimates of a finer timescale than that are going to be very noisy.

Anything that reports the network's hashrate is a very very vague estimate as it can only be observed indirectly by block times, and blocks are somewhat infrequent.  Some reporting tools miscalculate the hashrate around retargeting because they apply the wrong difficulty (the earlier block's difficulty) or because they switch to a single block integration interval.

There is very little a miner can do to influence the hashrate by turning on and off for just a brief period... and it doesn't really matter where in the cycle they do it. Moreover, whatever influence they achieve is just balanced out by the next cycle. There should be no way to increase your income from doing this, and it's very easy to decrease it (by letting other people get more of the blocks).

[evilscoop]

You didn't mention how you're measuring this. Pieter's dont seem to show that, and estimates of a finer timescale than that are going to be very noisy.

Anything that reports the network's hashrate is a very very vague estimate as it can only be observed indirectly by block times, and blocks are somewhat infrequent.  Some reporting tools miscalculate the hashrate around retargeting because they apply the wrong difficulty (the earlier block's difficulty) or because they switch to a single block integration interval.

There is very little a miner can do to influence the hashrate by turning on and off for just a brief period... and it doesn't really matter where in the cycle they do it. Moreover, whatever influence they achieve is just balanced out by the next cycle. There should be no way to increase your income from doing this, and it's very easy to decrease it (by letting other people get more of the blocks).

see http://mining.thegenesisblock.com/

Also the graph you link does show the drop, from 800+ths to under 600ths
Its an interesting blip that does happen, might be a rich newbie who fails to understand how the diff is calculated though

[bcp19]

I've noticed that lately network hashrate drops briefly by ~10% (or more) just before a difficulty retarget. The most recent example of this was (yesterday) was about 100 TH/s.

Does this suggest that some of the large players are deliberately taking their estate offline in order to try and keep difficulty lower than it would otherwise be?

This would strategy would require that difficulty is calculated by the spot network hashrate at the changeover time - is that the case or is it based on a recent average?

Kate.

Most likely a lot of equipment was brought online to test and then taken offline to ship.  Turning off hardware at this point in time would have such a minimal effect that it's make more sense to mine all the coins you could up to the last second.  This difficulty spike means earnings from 100TH dropped roughly 27% as compared to the previous difficulty.  That means it might have dropped 27.1 or 27.2% had it stayed online.  More profits lost in that day than saved by 'lower difficulty'.

[GigaWave]

This is not the difficulty you are looking for....


I guess all my watching of the hash rate is nothing but a mirage.

[Morlock]

Now that you mention it. My miners went off line this morning during the change. I'll have to remember to note it if it happens again.  Since who knows if that is a trend or not. But I think I recall they went off line during the last change also.

Also who knows if there has been any ddoss on any mining pools before this change happens that could be a reason also.

Or even some company just happens to be testing there devices for a few days to burn them in before shipping.

It's an intresting thought.

[bcp19]

Now that you mention it. My miners went off line this morning during the change. I'll have to remember to note it if it happens again.  Since who knows if that is a trend or not. But I think I recall they went off line during the last change also.

Also who knows if there has been any ddoss on any mining pools before this change happens that could be a reason also.

Or even some company just happens to be testing there devices for a few days to burn them in before shipping.

It's an intresting thought.

I would bet the burn-in to be the most likely cause.  We'll be seeing it back on the network in a few days to a week.

[thy]

I've noticed that lately network hashrate drops briefly by ~10% (or more) just before a difficulty retarget. The most recent example of this was (yesterday) was about 100 TH/s.

Does this suggest that some of the large players are deliberately taking their estate offline in order to try and keep difficulty lower than it would otherwise be?

This would strategy would require that difficulty is calculated by the spot network hashrate at the changeover time - is that the case or is it based on a recent average?

Kate.

I would rather suspect that it is some scammy ASICcompany that holds customers ASICS a few days extra and mines with them and orders pickup for big batches for around the time they predicts the next difficulty change is about to happen and sends them out then. Hashrate then recovers a few days later when they scamcompanys have got themself up a decent set of customers miners that they yet again mines with and the delivered miners also start to arrive at customers after from a few days up to maby 10 days later depending on how far away in the world people who bought the miners is located.