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Query data from M_DISK_USAGE take very long time

Mar 12 at 10:04 AM

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Hi,

It takes more than 8 minutes to get date from M_DISK_USAGE when I executed the following SQL statement:

select * from M_disk_usage

Although it returned only 8 records.

Any idea on this?

10 |10000 characters needed characters left characters exceeded

What HANA version are you using?

Is it a scale-out or single host system?

Is it using local file systems or NFS?

What file system type is being used here anyhow?

Have you checked any SAP notes?

Are there many trace files and/or backup files in the system's folders?

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Hi Lars,

My team is working with another team. We try to monitor their HANA systems by our own defined charts.

The HANA version which they are using is: 1.00.122.14.1511357770. Scale-out systems. Using NFS.

I already checked in the SAP notes but I have not got any regarding information.

Do you have any experience on this issue?

Thanks,

Anh

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Hey Anh

checking M_DISK_USAGE with EXPLAIN PLAN you can see that it is querying several other monitoring views:

  • SYS.M_VOLUMES
  • SYS.M_VOLUME_SIZES
  • SYS.M_BACKUP_SIZE_
  • SYS.M_TRACEFILES

A first step in the analysis would be to see whether any of those views is specifically slow.

Also, since you are using a scale-out setup, it's relevant to understand that these monitoring views internally have to communicate with the nameserver. That means there is some network traffic involved, which could be a hint towards the cause of the problem.

So, checking the inter-node network connections might be a good idea.

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