Synthetic Full Size

[BrandanC]

Hello,

We have recently upgraded our file clusters to Windows Sever 2019, Following this we created a new Windows Computer Backup job - failover cluster. This time we decided to use synthetic fulls weekly, the first full backup was around 1.3TB in size which is small as the old job backing up the same clusters was around 12TB. The second week the synthetic full was 40TB after dedup and compression. This is excessively large as the job only reads 14TB worth of data, this is now re-occuring every synthetic full.

Has anyone experienced this? or does anyone know possible causes/resolution. everything seems the same as previous bar the file clusters OS version and that we are using synthetic fulls instead of active fulls.

[HannesK]

Hello,
and welcome to the forums.

That all sounds very strange and makes no sense from a technical perspective to me. Please open a support case and post the case number here for reference.

Thanks,
Hannes

[BrandanC]

Hello,

Many thanks for your reply, i have raised a support case prior to me posting this and so far we've made no progress. - Case # 0376826

I've been advised to enable defragment and compact however i cant as it flags an error "Defragment and Compact is unnecessary when periodic full are enabled”.