FAQ

How to override playbook variables

You might have noticed that many Ansible commands in the documentation use -e somevar=value to specify variables.

This variable declaration takes precedence over any other pre-defined variables.

An easy approach to override variables in the files found in group_vars/all/ path is to override them.

The reason is that if you edit any of these files you risk a conflict when updates are pulled from the iri-playbook repository.

Overriding file variables

The files in group_vars/all/ are read in alphabetic order.

For example: you have a file called aaa.yaml with the variable test_var:

test_var: 1234

and you have a file called bbb.yaml, also with the variable test_var:

test_var: abcd

When the playbook runs, it first reads the file aaa.yaml and then bbb.yaml. test_var ends up with the value abcd.

Best practice is to create a file starting with the letter z, for example zzz-myenvironment.yaml and in it define all the variables you want.

How to tell if my node is synced

You can check if your node is synced by looking at iota-pm GUI. Check if Latest Mile Stone Index and Latest Solid Mile Stone Index are equal:

synced_milestone

Another option is to run the following command on the server’s command line (make sure the port matches your IRI API port):

curl -s http://localhost:14265 -X POST  -H 'X-IOTA-API-Version: 1' -H 'Content-Type: application/json' -d '{"command": "getNodeInfo"}'| jq '.latestSolidSubtangleMilestoneIndex, .latestMilestoneIndex'

This will output 2 numbers which should be equal.

Note

Above command will fail if you don’t have jq installed. See below how to install it.

You can install jq:

Ubuntu: apt-get install jq -y

Centos: yum install jq -y

Alternatively, use python:

curl -s http://localhost:14265 -X POST  -H 'X-IOTA-API-Version: 1' -H 'Content-Type: application/json' -d '{"command": "getNodeInfo"}'|python -m json.tool|egrep "latestSolidSubtangleMilestoneIndex|latestMilestoneIndex"

If you have problems getting in sync after a very long time, consider downloading a fully synced database as described here: Where can I get a fully synced database to help kick start my node

If the issue still persists, perhaps difficulties syncing are related to this: whyAmISeeingUDPBadLength

How do I tell if I am syncing with my neighbors

You can use IOTA Peer Manager. Have a look at the neighbors boxes. They normally turn red after a while if there’s no sync between you and their node. Here’s an example of a healthy neighbor, you can see it is also sending new transactions (green line) and the value of New Transactions increases in time:

health_neighbor

Where to get the latest milestone index from

It used to be possible via the botbox on Slack. And since Slack is no longer in use, you can get it by running:

curl -s https://x-vps.com/lmsi | jq .

This is a value which is based on querying approximately 100 full nodes.

At time of writing, we are still waiting for the official botbox to be added to IOTA’s Discord chat application.

Why is latestSolidSubtangleMilestoneIndex always behind latestMilestoneIndex

This is probably the most frequently asked question.

At time of writing, and to the best of my knowledge, there is not one definitive answer. There are probably various factors that might keep the Solid milestone from ever reaching the latest one and thus remaining not fully synced.

I have noticed that this problem exacerbates when the database is relatively large (5GB+). This is mostly never a problem right after a snapshot, when things run much smoother. This might also be related to ongoing “bad” spam attacks directed against the network.

Some things to try:

How to get my node swap less

You can always completely turn off swap, which is not always the best solution. Using less swap (max 1GB) can be helpful at times to avoid some OOM killers (out-of-memory).

As a simple solution you can change the “swappiness” of your linux system. I have a 8GB 4 core VPS, I lowered the swappiness down to 1. You can start with a value of 10, or 5. Run these two commands:

echo "vm.swappiness = 1" >>/etc/sysctl.conf

and:

sysctl -p

You might need to restart IRI in order for it to adapt to the new setting. Try to monitor the memory usage using free -m, swap in particular, e.g.:

free -m
              total        used        free      shared  buff/cache   available
Mem:           7822        3331         692         117        3798        4030
Swap:          3815           1        3814

You’ll see that in this example nothing is being used. If a large “used” value appears for Swap, it might be a good idea to lower the value and restart IRI.

What are the revalidate and rescan options for

Here’s a brief explanation what each does, courtesy of Alon Elmaliah:

Revalidate “drops” the stored solid milestone “table”. So all the milestones are revalidated once the node starts (checks signatures, balances etc). This is used it you take a DB from someone else, or have an issue with solid milestones acting out.
Rescan drops all the tables, except for the raw transaction trits, and re stores the transactions (refilling the metadata, address indexes etc) - this is used when a migration is needed when the DB schema changes mostly.

It is possible to add these options to the IRI configuration file (or startup command):

--revalidate or --rescan.

If you have used this installation’s tutorial / automation, you will find the configuration file in the following location:

On Ubuntu: /etc/default/iri
On CentOS: /etc/sysconfig/iri

You will see the OPTIONS variable, so you can tweak it like so:

OPTIONS="--rescan"

and restart IRI to take effect: systemctl restart iri

Note

Once you’ve restarted the service with the --rescan or --revalidate options you can remove the option from the configuration file. If it stays in the configuration file, subsequent restarts will use that option again, perhaps when you do not explicitly choose to enable it.

Where can I get a fully synced database to help kick start my node

For the sake of the community, I regularly create a copy of a fully synced database.

You can use the iric tool to download and install the database Fullnode IRI Configuration Utility, or update manually using the following instructions:

NOTE I am providing this database copy to help the community. Making this possible involves increasing costs due to the frequent downloads/bandwidth usage. Please consider donating to help keep this possible:

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  • The full command will only work if you’ve installed your full node using this tutorial/playbook.
systemctl stop iri && rm -rf /var/lib/iri/target/mainnetdb* && mkdir /var/lib/iri/target/mainnetdb && cd /var/lib/iri/target/mainnetdb && wget -O - https://x-vps.com/iota.db.tgz | tar zxv && chown iri.iri /var/lib/iri -R && systemctl start iri

Note

There was some debate on the slack channel whether after having imported a foreign database if it is required to run IRI with the --revalidate or --rescan flags. Some said they got fully synced without any of these.

To shed some light on what these options actually do, you can read about it in What are the revalidate and rescan options for

I try to connect the light wallet to my node but get connection refused

There are commonly two reasons for this to happen:

If your full node is on a different machine from where the light wallet is running from, there might be a firewall between, or, your full node is not configured to accept external connections.

See Full Node Remote Access