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mohit1234 avatar image
mohit1234 asked Erick Ramirez answered

How do I identify write size and read size of an existing cluster?

I was checking expected pricing of datastax astra using calculator but i am not able to understand what should i given in write size and read size parameter values.

Could you please guide how can i find those values from my existing cluster is there any metrics which i should check or any other method available in opscenter graphs?

astra db
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starlord avatar image
starlord answered Erick Ramirez edited

There are some metrics around read requests available in OpsCenter:

OS: Disk Request Size [os-disk-request-size]
Average size of read requests issued to the disk.
OS: Disk Request Size [os-disk-request-size-kb]
Average size of read requests issued to the disk.

For writes however there are no OpsCenter metrics around the size, but you could get an estimate on the max size by summing the data types for the table in question:

https://docs.datastax.com/en/cql-oss/3.1/cql/cql_reference/cql_data_types_c.html

You'll really need to get that info from the application though, that's the only real way to see what you are Inserting to know the size.

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Erick Ramirez avatar image
Erick Ramirez answered

You can use a combination of the nodetool tablestats and nodetool tablehistograms outputs in order to get an estimate.

You can get the average partition size from the tablestats output while the tablehistograms output will give you the partition sizes read/written in the last 15 minutes.

If you need assistance, feel free to click on the Chat with an Expert button on the Astra DB pricing page. Cheers!

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