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DCRUM Upgrade - Database disk space requirements

john_leight
Dynatrace Pro
Dynatrace Pro

When upgrading DCRUM the program checks for necessary database disk space to be available. I cannot find any documentation on how much free space is required (compared to the size of tables or database size). I believe it looks for the amount of free space to be equal to the database size.

Can someone verify the required amount of free space required to do an upgrade?

When performing an upgrade it looks like it copies a table to a temp space, rebuilds the table, and restores the data.

How much space does the upgrade really require when upgrading the database?

4 REPLIES 4

chris_v
Dynatrace Pro
Dynatrace Pro

I can only add anecdote here John, but from what I've seen in the field. You can need up to triple the size of each table.

old + new + log space*.

And it appears to upgrade tables in groups rather than individually. So yes a doubling of the actual DB size seems a safe estimate.

*be particularly aware of this as the log is often stored in a different location with potentially a different size limit on it.

john_leight
Dynatrace Pro
Dynatrace Pro

The reason for the question is that many times there is not a full "database size" of free disk space available on the drive where the database is housed. So does the upgrade really need free space equaling the database size - or is there some other calculation that can be used to determine the real amount of free space available? Is there some other way to upgrade the CAS database, like specifying a different backup drive for the upgrade process?

john_leight
Dynatrace Pro
Dynatrace Pro

Is there any way to get a more accurate estimate on the size required for an upgrade?

In this case there is a 579 GB volume and the database file is taking up 379 GB with 200 GB free. This was after a database shrink in MS SQL. During the upgrade we do not see any additional disk space being used by the upgrade process - unless we missed when it increased.

chris_v
Dynatrace Pro
Dynatrace Pro

Some upgrades don't do much to the database schema and won't need much space, others do lots of changes and will use a lot of space. It would be nice to have some forewarning from the labs/release notes.

I understand the trepidation some customers have around increasing the available storage, some times it really easy, they can dynamically increase some SAN storage other times it's a physical machine and requires actually adding more disks so not easy.