# Backup Estimation

**URL:** <https://discuss.aerospike.com/t/backup-estimation/3824>\
**Category:** asbackup & asrestore\
**Created:** [February 2, 2017, 1:08pm UTC](https://discuss.aerospike.com/t/backup-estimation/3824 "2017-02-02T13:08:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![alexkru](https://avatars.discourse-cdn.com/v4/letter/a/cc9497/32.png) [@alexkru](https://discuss.aerospike.com/u/alexkru)\
**Post date:** [February 2, 2017, 1:08pm UTC](https://discuss.aerospike.com/t/backup-estimation/3824/1 "2017-02-02T13:08:08Z")

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Hi, I want to perform a backup through asbackup but at first I want to estimate the volume of the backup file. On one of our production clusters we have 23 nodes with replication factor of 2, on the AMC I see 13.14 TB Cluster Disk Usage and 1.34TB Cluster Ram Usage. We use a single single namespace that has over 11 bilion of records. When I run the following command: asbackup -n \<namespace\_name\> --estimate and I see to following output:

> 2017-02-02 12:47:53 GMT [INF] [31289] Backed up 10000 record(s), 0 secondary index(es), 0 UDF file(s) from 23 node(s), 6500722 byte(s) in total (~650 B/rec) 2017-02-02 12:47:53 GMT [INF] [31271] Estimated overall record size is 679 byte(s)

I don`t think that these numbers add up, how can I find an estimation for the backup that would be as close as possible to the real size?

EDIT: If I understood it correctly, the backup size is 679\*11,000,000,000 (~number of records), which ends up as 7.469TB. Did I got it right?

Thanks, Alex.

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**Author:** ![pgupta](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.aerospike.com/pgupta/32/2351_2.png) [@pgupta](https://discuss.aerospike.com/u/pgupta)\
**Post date:** [February 3, 2017, 1:06am UTC](https://discuss.aerospike.com/t/backup-estimation/3824/2 "2017-02-03T01:06:07Z")

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See [asbackup command-line options | Aerospike Documentation](http://www.aerospike.com/docs/tools/backup/asbackup.html)

When passing the --estimate command line option to asbackup (and skipping --directory and --output-file), **asbackup creates a temporary test backup of 10,000 records** from the namespace. It then outputs, based on the observed record sizes, an estimate of the average size of a record in the backup. In order to estimate the total size of the backup file or files, **multiply this size by the number of records in the namespace and add 10% for indexes and overhead**.