Data Domain File system settings

[stewsie]

I am working with Veeam support to investigate slow copy job performance from Data Domain (backup target) to Data Domain (copy target). Yes I know this may not be the best option however I am looking to try and make the best of a bad situation

Has anyone changed any of the File System Settings on the DD specifically Workload Balance?

We have it set to

Random Workloads 10%
Sequential Workloads 90%

I didn't set this up and don't know if this is the default setting. I am not the expert but I thought the Veeam data would be written randomly.

Majority of backups are taking weekly synthetic full and active monthly full

[gmajestix]

I also had the same thoughts on workload balance settings on the DataDomain. However reading the documentation (https://www.delltechnologies.com/asset/ ... u95865.pdf) from Dell it doesnt really explain in detail how changing this settings will affect the performance of backups.

Table 92 Workload Balance settings
Workload Balance settings Description
Random workloads (%) Instant access and restores perform better using random
workloads.
Sequential workloads (%) Traditional backups and restores perform better with sequential
workloads.

My guess in your scenario is that when doing a backup copy from DD to DD is that is doesnt use the feature of Veeam "Accelerated Restore of Entire VM" (https://helpcenter.veeam.com/docs/backu ... ml?ver=120) which is used when doing a restore of a VM. Which makes sense as this is not a restore but a copy of a backup. Probably for restore purposes it is better to leave it at default settings (10% random, 90% sequential) because the feature Accelerated Restore of Entire VM assumes the following:

Dell Data Domain storage systems are optimized for sequential I/O operations. However, data blocks of VM disks in backup files are stored not sequentially, but in the random order. If data blocks of VM disks are read at random, the restore performance from backups on Dell Data Domain degrades.
To accelerate the restore process, Veeam Backup & Replication creates a map of data blocks in backup files. It uses the created map to read data blocks of VM disks from backup files sequentially, as they reside on disk. Veeam Backup & Replication writes data blocks to target in the order in which they come from the target Veeam Data Mover, restoring several VM disks in parallel.
This accelerated restore mechanism is enabled by default, and is used for the entire VM restore scenario.

I'm guessing changing workload balance will probably break the algorithm of Accelerated Restore of Entire VM and lead to unexpected consequences. But that is just my guessing. Maybe someone from Veeam can comment.