[Rudi Bruchez (rudi-bruchez)]

What's wrong

The "Prerequisites" section lists "Windows operating system". The option exists and works on SQL Server on Linux: on SQL Server 2025 it switches the default algorithm to ZSTD, and on SQL Server 2022 it can be set to 1. The Windows requirement belongs to Intel QAT (value 2), which the integrated acceleration page already covers: on Linux, value 2 is accepted, but a compressed backup then fails with error 17441 ("This operation requires Intel(R) QuickAssist Technology (QAT) libraries to be loaded").

The ZSTD entry also says the algorithm is "faster and more effective". At the default level it uses about half the CPU of MS_XPRESS, but the backup can be larger than with MS_XPRESS, depending on the data (measurements in the companion PR on backup-compression-sql-server.md: 653.8 MB in ZSTD against 597.5 MB in MS_XPRESS on a 1,422 MB database).

Evidence

SQL Server 2025 CU7 (17.0.4065.4), Enterprise Developer, Linux container. Fresh database; backup compression default and backup compression algorithm initially 0.

EXEC sp_configure 'backup compression default', 1; RECONFIGURE;
EXEC sp_configure 'backup compression algorithm', 3; RECONFIGURE;
BACKUP DATABASE verif_doc_algo_option TO DISK = N'/var/opt/mssql/data/vao_1.bak' WITH COPY_ONLY, FORMAT;
BACKUP DATABASE verif_doc_algo_option TO DISK = N'/var/opt/mssql/data/vao_2.bak' WITH COPY_ONLY, FORMAT, COMPRESSION;
EXEC sp_configure 'backup compression algorithm', 1; RECONFIGURE;
BACKUP DATABASE verif_doc_algo_option TO DISK = N'/var/opt/mssql/data/vao_3.bak' WITH COPY_ONLY, FORMAT;
SELECT name, compression_algorithm FROM msdb.dbo.backupset WHERE name LIKE N'vao %';

Observed: ZSTD, ZSTD, MS_XPRESS. The option isn't an advanced option (is_advanced = 0). On SQL Server 2022 CU27-GDR (16.0.4305.5), Linux, sp_configure 'backup compression algorithm', 1 succeeds and value_in_use becomes 1. Expected per the current text: the option unavailable outside Windows.

Change

Removes "Windows operating system" from the prerequisites, and replaces "faster and more effective" in the ZSTD entry with "At its default level, it uses less CPU than MS_XPRESS."

[prmerger-automator]

Rudi Bruchez (@rudi-bruchez) : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit f046eef:

✅ Validation status: passed

File	Status	Preview URL	Details
docs/database-engine/configure-windows/view-or-configure-the-backup-compression-algorithm-server-configuration-option.md	✅Succeeded

For more details, please refer to the build report.

[Diana Richards (v-dirichards)]

adpa-ms

Can you review the proposed changes?

Important: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team

[Copilot]

🟢 Approval recommended

The documentation changes clarify Linux support and make the ZSTD CPU-usage comparison more precise, with no active review issues identified.

No open issues 🎉

What changed in this PR

Updates the backup compression algorithm documentation to clarify Linux support and provide a more precise description of ZSTD's CPU usage.

Changes:

• Removes the Windows operating system prerequisite.
• Replaces the broad “faster and more effective” ZSTD claim with a default-level CPU comparison against MS_XPRESS.

File	Summary
docs/​database-engine/​configure-windows/​view-or-configure-the-backup-compression-algorithm-server-configuration-option.md	Updates prerequisites and ZSTD guidance. Nit: clarify that the Intel QAT algorithm remains Windows-only to avoid suggesting that value 2 is supported on Linux.

_{Review effort: Lite}