Recent low luck information1 week

Dear miners,

we would like to inform you that we have detected and resolved an unintentional block withholding attack.

The issue has been discovered a week ago and we have immediately taken an action by contacting the particular miner. The cause turned out to be a bug in a custom mining firmware, which has been promptly fixed by the miner. We have no indication that there was any bad intention. The fixed firmware solved two blocks since then so we can consider this issue as resolved.

A recent time period of worse luck can be at least partly attributed to this incident.

Block withholding attack is a well-known weakness of the whole pool mining principle and no public pool is immune against it.

As a by-product of the bad luck investigation, we have implemented a new method how to mathematically prove that the pool does not cheat on miners. This feature will be released after the public interface has been tweaked. The release is planned towards the end of next week.

Recent Orphaned Blocks Explanation3 months, 3 weeks

Orphaned blocks are natural part of Bitcoin network. Therefore, our recent orphan rate was probably - to a certain extent - a random noise. Since it has been higher than usual in the past few days, we have conducted a deep analysis of our internal infrastructure and made some adjustment.

Firstly, we have upgraded to Bitcoind 0.11.1 which definitely improved our mempool performance. However, the remaining problem was still in propagation of our blocks into the bitcoin network. Eventhough Slush Pool has been using the fast block relay network ( for over a year now, thorough analysis of block propagation times showed that our connections to the fast block relay network were not working properly in the last few weeks.

This connectivity issue, which affected all 9 bitcoin nodes that we currently operate, has been fixed with the help from Matt Corallo - the author of the fast block relay network. In addition, we have updated the relay network client to the latest version.

Since we have not experienced any orphaned block (invalid in Slush Pool terminology) in the last 2 days (or more than 30 consecutive blocks) we suppose the issue has been fixed. Moreover the block propagation times are now being carefully monitored and >we believe such increased attention will lead to stable validation in the future.

Finally we believe, the fast block relay network provides a very robust solution to this issue for all miners and mining pools.

Ending note:

Not only exchanges and wallets have been affected by persisting spam attack. Since pools depend on quick propagation times among Bitcoin network nodes, they were affected as well.

A very good analysis regarding this topic has been written and published on following website by Organ Ofcorti:

Although he covered a few selected pools in his analysis there are other big players who were not analyzed and had higher rate of orphaned blocks in the weeks before as well. Therefore, it is safe to guess that the whole network was and is being affected to much higher extent.

As to why the current spam attack impacts orphan rates, we would like to point attention of our technically skilled miners to following statistics as well:

Short Website Maintenance - 23. 9. - 24. 9.4 months, 3 weeks

We will be upgrading our web server infrastructure during the night from 23. 9. to 24. 9. The expected outtage is around 5 minutes. You will see the standard maintenance screen. Mining operation will not be impacted.

Update: BIP101 voting disabled because of DDoS attack 5 months, 3 weeks

We were forced to switch voting ports 3301 to normal mining operation. The BIP101 voting has been suspended for now.

Please, use the regular ports 3333 for now. We'll keep you updated.

Servers Location Address
USA, east coast stratum+tcp://
Europe stratum+tcp://
China, mainland stratum+tcp://
Asia-Pacific/Singapore stratum+tcp://

Enjoy Namecoin Merged-mining6 months, 1 week


Most of you are already probably aware of our new NameCoin merged-mining operation which was in development for the most part of this year. It has been thoroughly tested in the past month and now is being published.

However, until today you had little chance to see and track all your rewards. The new UI now provides all merged mining related data .

So what to check exactly for? There are 2 sections on our web which were adjusted for this purpose and they are as follows:

Block History

The top right corner has a slide switch that allows switching between Bitcoin and Namecoin block history.

Rewards History

The top right corner has a slide switch that enables showing rewards for all Namecoin blocks interleaved with Bitcoin blocks. Statistics which we provide for Namecoin blocks is pretty much the same as for Bitcoin except values in the "Block Value” column. Let us explain.

Since we do not distribute Namecoin rewards to Namecoin payout wallets we are using an external service to automatically ex-change all mined Namecoins to Bitcoins. Therefore, Your Reward column displays the amount of Bitcoins that belong to you after we have traded the Namecoin block. The Bitcoins for the traded Namecoin Block are being fairly distributed among miners based on the same scoring hash-rate formula which we use for Bitcoin rewards distribution. The Block Value column shows the exchange rate provided by and the amount of Namecoins you have been rewarded.

PS: The same rules for invalid blocks are applied which means no reward for invalid block.

0% fee for August6 months, 1 week

We have sunk the mining fee to 0 % for the month of August (3.8.2015 - 3.9.2015). It is already active. We hope all of you will enjoy your free mining. Feel free to invite your friends!

Thank you for your attention and enjoy our LUCKY mining summer with us.

Expanding Eastern Hemisphere Presence10 months, 2 weeks

Hello to all miners from eastern hemisphere! You can now connect to our mining servers in mainland China (Beijing) and Asia-Pacific(Singapore). This should provide connectivity not only to Asian miners but even for miners in Australia.

Slush pool website in local language

Our current users can also benefit from the new region-specific stratum server domain names.

Domain names for each region

— Slush Pool Team

Merged Mining in development!11 months

Now that we have started development activities on the most demanded user proposals, we're glad to announce that merged mining is on the way and it has top priority.

We're watching the Development Corner closely as there's a lot of important feedback for us. Quite a number of proposals have been implemented with a new version of the dashboard and some are now being worked on.

If you have submitted a proposal and it is neither rejected nor accepted for voting yet, be sure it will be processed soon. We have received quite a long list, which is great but takes some time to go through ;)

— Slush Pool Team

Changes in Monitoring11 months

After identifying the optimal use of our monitoring system we have decided to simplify few things:

  • Now only workers are being monitored. Account monitoring has been removed since we detected an unpleasant behavior in some corner cases. Users who have used account monitoring only (without worker monitoring), please reconfigure your account to use worker monitoring.
  • “Expected hash rate” setting has been renamed to “Alert limit” for clarity (see its explanation).

You can read full description of the Monitoring in a User Manual.

— Slush Pool Team

New Dashboard and Features11 months

We've received quite a lot of feedback to user interface since the new web pages release. We'd like to let you know that we're listening and that we work on development of your proposals.

Most notable changes that are now being rolled out is the new dashboard design and couple of other UI tweaks. Here's a list of the features:

  • Redesigned dashboard with new data - automatically refreshed every minute
  • “Pool statistics page” has autorefreshing enabled, including all charts
  • Notifications – gives you the important info right on the dashboard
  • All rewards can now be shown in BTC, mBTC, USD, EUR or CNY using the current prices (see Settings).
  • Language preference now applies to the whole system including email notifications
  • Support for local time zones - all time information are shown in your selected time zone - including emails (see Settings).
  • Plenty of other small changes.

These changes closed more then 10 user proposals, you can now vote here for other ideas!

— Slush Pool Team
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    #captainspeaking, AMA with the Founder, Marek Palatinus, TODAY! Do not miss an opportunity to ask whatever comes to your mind.

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    #captainspeaking Starting yesterday, after some testing period with bitcoin core 0.11.2, we have switched block version to v4. ...

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