What you’re seeing
- A nightly incremental that used to finish in minutes now runs for hours.
- The job log shows "CBT data is invalid" or that changed block tracking was reset, so the whole disk is read.
- Processed data equals the full disk size each night even though little has changed.
- The slowdown began right after a power outage, an unplanned host reboot or moving the VM to another host.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- Changed block tracking was reset by a hard shutdown, a crash or a hypervisor upgrade.
- A VM was migrated, restored or had its disks resized, which invalidates the tracking data.
- On physical servers, the Veeam change tracking driver is missing or failed to load after a Windows update.
- A snapshot from another tool was left behind and interferes with block tracking.
- Antivirus or defragmentation runs changed far more disk blocks than normal.
Why it matters
When every backup reads the whole server, jobs overrun their windows, slow down production systems during business hours and push other jobs later. Storage fills faster, offsite copies fall behind and the next night's backups may be skipped. If the condition persists, the business ends up with fewer restore points and slower systems at the same time.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Will this fix itself?
Sometimes it clears after one full read, but when it keeps happening there is an ongoing cause, such as a failed driver or leftover snapshot, that needs attention.
Is our data still being backed up?
Generally yes, just inefficiently. The concern is jobs overrunning and missing their window, which leads to gaps.