Slow backup performance

[Ribeiro Francisco]

Hello,

We have the following scenario:

A Lenovo Server with 64GB Memory and an Intel(R) Xeon(R) Silver 4314 CPU @ 2.40GHz processor with a fibre channel connection to a SAN switch, through a QLogic adapter.

An IBM Power 10 connected to the same SAN switch, with a linux partition to test the backup performance

The Lenovo VTL server as a LUN created in an IBM storage (SSD disks). The linux partition also have SSD disks.

If we write in that LUN using the VTL, we have no performance issues. If we write in the linux IBM partition disks using the linux partition we do not have any performance problem. But if we try to copy files to the VTL using the linux partition (or even the IBMi), it takes twice the time to do the same backup to a real Tape. Is it normal? We are not using compression or deduplication.

Kind Regards

[QUADStor VTL Support]

Hi,

Please send the diagnostic logs (HTML UI -> System Page -> Run Diagnostics -> Submit). You can send the logs to vtlsu...@quadstor.com

Is the backup to physical tape connected to the same partition ? What is the backup speed to physical tape ?

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[Ribeiro Francisco]

Hello,

I've deleted my previous reply since you asked me to send the logs to that specific email.

Logs were sent.

Also, yes, the physical tape is connected to the same partition.

Kind regards

[QUADStor VTL Support]

Hi,

There are two VTL HBA ports. One of them should be set to initiator mode while the other should be set to target-mode. 

This will help segregate tape  and disk transfers. 

The mode can be changed from the GUI "Access Management" page.

Under "Target Port Configuration" for one WWPN click on Modify and select Initiator and for the other WWPN select "Target"

The switch zoning can be changed appropriately to allow access for the hosts to only the target mode WWPN.

From one of the drive statistics

write_bytes_processed: 1335859200

write_cmds: 260910

This is an average of 5120  bytes per command which is very small.

There were other backups but it looks like the system was restarted and this was the only backup for which we have stats maintained.

Which backup application is used to copy files from the linux partition ? Is LTFS being used ?

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[Ribeiro Francisco]

Hello,

In IBMi we are using BRMS. In Linux we're using the tar command without z option.

We are going to try to modify the port mode and I'll report you back.

Kind regards 

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[Ribeiro Francisco]

Hi,

After adjusting the block size parameter in my tar command I was able to get the desired speeds. Is there any setting that we should adjust in the quadstor configure?

Kind regars

[QUADStor VTL Support]

Hi,

The correct block size and separating the ports for target and initiator traffic should be sufficient. If performance is preferred over space savings, non-dedupe pools will always give consistent performance and is not data dependent like the dedupe pools. 

For the disks/luns configured in the physical storage do not use thin provisioned luns. 

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[Ribeiro Francisco]

Hello,

Thanks for the tip. It seems that we cannot define the block size in the BRMS software. Is there any way to specify it in the VTL structure?

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[QUADStor VTL Support]

Hi,

Please set USEOPTBLK to *YES

https://www.ibm.com/support/pages/save-command-parameters-affect-performance

USEOPTBLK(*YES) DTACPR(*DEV) COMPACT(*DEV) 

There isn't a way to set a specific blocks size, but with the above 256k block size should be used

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