Data corruption due to unreliable SMB (CIFS) shares

KB ID: 3124
Product: Veeam Backup & Replication
Version: Any
Published: 2020-03-17
Last Modified: 2021-06-08
Get weekly article updates
By subscribing, you are agreeing to have your personal information managed in accordance with the terms of Veeam's Privacy Policy.

Cheers for trusting us with the spot in your mailbox!

Now you’re less likely to miss what’s been brewing in our knowledge base with this weekly digest

error icon

Oops! Something went wrong.

Please try again later.

Challenge

Storages that use the SMB (CIFS) protocol without the continuous availability and write-through features can cause data corruption in case of technical outages. This can lead to restore or backup problems.

Cause

If shares operate without the continuous availability feature in the write-though mode, data can end up in the “undefined” state in one of the many caches (RAM, hard disk cache, etc.) between the source and the disk. Many SMB (CIFS) NAS filers handle data on the “best effort” to gain better performance instead of safe data handling. 

Solution

SMB 3.0 continuous availability or transparent failover ensures high availability of the SMB file share.
Write-through capabilities with SMB guarantee that data written to the share will be written to the persistent storage (hard disks, SSDs, etc.). That means that the storage system only acknowledges a successful write after the data is stored successfully to the physical storage.
User-added image

Requirements for the SMB NAS filer:
  • Option A: Windows failover cluster with the file server role installed and the share configured in the “Continuous Availability” mode.
  • Option B: NAS storage with at least two controllers supporting SMB 3.0, “Continuous Availability” and “write-through” support.
These requirements are similar to other applications that require reliable storage (e.g. SQL or Hyper-V).

More information

The Veeam storage level corruption guard (Health Check) can detect corrupted backup files.
See this Microsoft Tech-Community article for more information on SMB share high availability.
Click here to send feedback regarding this KB, or suggest content for a new KB.
To report a typo on this page, highlight the typo with your mouse and press CTRL + Enter.

Spelling error in text

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Thank you!

Thank you!

Your feedback has been received and will be reviewed.

Oops! Something went wrong.

Please try again later.

KB Feedback/Suggestion

This form is only for KB Feedback/Suggestions, if you need help with the software open a support case

By submitting, you are agreeing to have your personal information managed in accordance with the terms of Veeam's Privacy Policy.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Verify your email to continue your product download
We've sent a verification code to:
  • Incorrect verification code. Please try again.
An email with a verification code was just sent to
Didn't receive the code? Click to resend in sec
Didn't receive the code? Click to resend
Thank you!

Thank you!

Your feedback has been received and will be reviewed.

error icon

Oops! Something went wrong.

Please try again later.