[Openstack-operators] [Nova] How common is user_data for instances?

Michael Still michael.still at canonical.com
Sat Aug 11 09:12:22 UTC 2012


I'm seeking information about how common user_data is for instances in
nova. Specifically for large deployments (rackspace and HP, here's
looking at you). What sort of costs would be associated with changing
the data type of the user_data column in the nova database?

Bug 1035055 [1] requests that we allow user_data of more than 65,535
bytes per instance. Note that this size is a base64 encoded version of
the data, so that's only a bit under 50k of data. This is because the
data is a sqlalchemy Text column.

We could convert to a LongText column, which allows 2^32 worth of data,
but I want to understand the cost to operators of that change some more.
Is user_data really common? Do you think people would start uploading
much bigger user_data? Do you care?


1: https://bugs.launchpad.net/nova/+bug/1035055

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