Running ScyllaDB on AWS, how to use EBS volumes, ephemeral storage reboot or restart

[Guy]

Originally from the User Slack

@채수상_(soo): hello. I’m trying to use scylladb for the first time…
I ran scylladb using the combination of ami image and i3.xlarge as instructed in the scylla document.
Afterwards, I stopped the instance and started it again, but the instance storage was not mounted and scylla-server was not running.

I have a question.

1. How do I mount it again after rebooting?
2. When I turn on an instance using an ami image, will all my data be lost if I reboot it?

@fodo: seems like more of aws questions rather than scylla :simple_smile:

1. you should mount your device via fstab. https://docs.aws.amazon.com/ebs/latest/userguide/ebs-using-volumes.html
2. since i type machine is local-ssd ec2 so your data in local sdd can be gone after restart

@채수상_(soo): Yes, that’s right. It seems like a question related to Linux and AWS.
However, I used ami produced by scylla, and it seems that ephemral storage is automatically mounted when booting and DB is installed on that storage.

I wonder if I can simply mount the storage in fstab, reboot, and start scylla-server, or if I need to make additional settings.

@fodo: IIRC scylladb ami will mount it for you automatically
https://github.com/scylladb/scylla-machine-image/blob/next/common/scylla_create_devices

If your concern is about data loss, it’s data will be lost after restart since it’s “i type” which means its data layer uses local ssd. it’s not ebs

so when you need to restart scylladb node, make sure that you have replication factor > 1 for your data to replicate over other nodes

@avi: AWS i3 have ephemeral storage, do not stop and start them. You can reboot them.
btw, use i4i, they’re much better than i3

@채수상_(soo): Thanks, I’ll try using i4i.

[Chris]

Want to understand something here. It seems the recommendation is to not stop/start the instance. What I am not understanding is how to ensure data retention in if the instance goes down outside our control. Is that just not possible with a replication factor of 1?