Ok so today everyone noticed a few splits between primarily guardian and hub and a couple between spirit and hub. I have not posted much at all previously about what net splits actually are or how they work so I'll attempt to do so in this post.

Firstly, the net splits today were due to routing problems in which we assume was something between our east coast and west coast data centres. Re-routing traffic through different providers is the best that can be done but that in itself causes a further net split in nearly all cases.

Now a little more into the explanations.

What is a Net Split?

A Net Split is when for one reason or another a hub server loses it's connection with a client server. During this event you will notice a large amount of people quitting with a quit message similar to (hub.seersirc.net spirit.il.us.seersirc.net). Depending on which 'side' of the split you are on depends on the severity. If in this case you are on spirit you will notice a larger impact with all users not on your server 'quitting' from IRC. If however you're on the rest of the networks side you'll only notice those on spirit 'quit'. Once the two servers recover their connection you get the opposite, everyone on the 'other side' of the split will then rejoin.

What causes Net Splits?

Net splits are more often than not caused by:

1. Routing issues between server datacentres and loss of service while routing is changed to different providers (most common 4-5 times /yr)
2. We have restarted or rerouted servers during a maintenance period to update something (uncommon 2-3 times /yr)
3. Denial of Service. Either caused by something internally (bug in some software) or caused by an external attack (rare 1-2 times /yr)
4. A server actually shuts down/turns off/crashes for some reason (most rare)

What does SeersIRC do about them?

Firstly, we take great care in making sure any servers linked to the network have good redundant links and are secure and stable. This alone provides us with a great deal of passive protection against them. We also regularly check and monitor our links to try and remove a server before issues happen.

During the event of every net split we do our best to quickly locate the issue and resolve it, we also endeavour to keep everyone updated during the process usually via network or server wide globals.

Going by the above list of causes, #1 there is little we can do but wait for the routing to settle after it has been changed, as was the case today. #3 and #4 we can't usually do a great deal about but wait for our data centre hosts to assist us in correcting it and #2 we are in full control over the net splits so although they are still annoying we can prepare and plan for the outages.

What can we do during netsplits?

If you find you're 'wrong' side of a net split you usually can't talk to services (identify with nickserv etc). You can see the status of the network at any time by typing /MAP. If you only see one server listed here it is likely you're on the worst hit side. To rectify this you have a few options.

1. Try to keep an eye out for our globals/news posts about maintenance as if that's the case your server will reconnect shortly
2. Use the Servers Page found here and pick another server to connect to by /server servername.seersirc.net
3. Wait it out as more often than not the problem is fixed within 5 minutes.

If you find yourself at any time, during net splits or not unable to connect to a specific server try another one by using the method mentioned in #2 above.

So can you sum it up for me?

Net Splits are caused by servers losing their connections between each other for one reason or another. During the event you may get cut off from the rest of the network, in which case you can use the Servers Page found here to pick another server to connect to. Netsplits frustrate not only all of you but also the staff as well and we do everything in our power to prevent and limit the effect of them when they do on occasion occur.

If you have any further questions regarding outages both planned and unplanned or net splits in general don't hesitate to contact me on IRC, post here or email admin@seersirc.net and someone will get back to you.

good topic sir! im glad netsplits arent that often in seersirc compared to swiftirc and others

Thanks for the explenation

Cheers Niph.

The boss has spoken