zstd - Fast Compression

zstd (Zstandard) is a modern compressor with an unusually good speed-to-ratio trade-off. For WordPress VPS operations, it is a strong default for database dumps and for directory backups when paired with tar (.tar.zst).

Quick Summary

• Compress: zstd file.sql -> file.sql.zst
• Decompress: zstd -d file.sql.zst or unzstd file.sql.zst
• Test: zstd --test file.sql.zst
• Directory backup: tar -I zstd -cvf wp-files.tar.zst /var/www/html

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When to use zstd

Use zstd when:

• You want fast backups and fast restores.
• You compress large SQL dumps, log bundles, and WordPress file archives.
• You want a good default compression algorithm for automation.

If you need maximum compression for cold storage, consider xz (and accept the time cost).

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Prerequisites

• Ubuntu 22 / 24 LTS VPS.

• Installed zstd and tar utilities.

• Basic file permission & path knowledge.

• Access to WordPress directories such as:

  /home/dev_wpstrategist/public_html/, /home/wpbackup/, /var/log/.

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Core syntax

zstd-core-syntax.sh

# ──────────────────────────────
# 1. Compress a single file (same location)
zstd [OPTION] [INPUT_FILE]

# Example:
zstd /home/dev_wpstrategist/error.log
# → Output: /home/dev_wpstrategist/error.log.zst

# ──────────────────────────────
# 2. Decompress a .zst file
unzstd [INPUT_FILE.zst]
# or
zstd -d [INPUT_FILE.zst]

# Example:
zstd -d /home/dev_wpstrategist/error.log.zst
# → Output: /home/dev_wpstrategist/error.log

# ──────────────────────────────
# 3. Compress with specific level (1–19)
zstd -# [INPUT_FILE]

# Example (max compression):
zstd -19 /home/wpbackup/db.sql
# → Output: db.sql.zst (highest ratio, slower)

# ──────────────────────────────
# 4. Compress and save to another directory
zstd -o [OUTPUT_PATH] [INPUT_FILE]

# Example:
zstd -o /home/wpbackup/db_$(date +%F).sql.zst /home/dev_wpstrategist/db.sql

# ──────────────────────────────
# 5. View compression statistics
zstd -v [INPUT_FILE]

# ──────────────────────────────
# 6. Combine with tar to create a .tar.zst archive (Export)
tar -I zstd -cvf [OUTPUT].tar.zst [SOURCE_DIR]

# Example:
tar -I zstd -cvf /home/wpbackup/wpfiles_$(date +%F).tar.zst /home/dev_wpstrategist/public_html

# ──────────────────────────────
# 7. Extract a .tar.zst archive (Import)
tar -I zstd -xvf [INPUT].tar.zst -C [TARGET_DIR]

# Example:
tar -I zstd -xvf /home/wpbackup/wpfiles_2025-10-25.tar.zst -C /home/dev_wpstrategist/public_html/

# ──────────────────────────────
# 8. Stream backup over SSH
tar -I zstd -cvf - [SOURCE_DIR] | ssh root@remote "cat > /backup/wp_$(date +%F).tar.zst"

# ──────────────────────────────
# 9. Dump & compress WordPress DB
mysqldump -u [USER] -p'[PASS]' [DB_NAME] | zstd -19 -o /home/wpbackup/db_$(date +%F).sql.zst

# ──────────────────────────────
# 10. Decompress & import DB
zstd -dc [INPUT].sql.zst | mysql -u [USER] -p'[PASS]' [DB_NAME]

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Key options

Option	Description	Example	Use Case	CPU Impact
-#	Compression level 1–19	zstd -9 file.sql	Adjust ratio vs speed	🟢 Low–🟡 Medium
-d	Decompress file	zstd -d file.zst	Restore backups	🟢
-o	Output file path	zstd -o /dest/out.zst file	Store elsewhere	🟢
-v	Verbose	zstd -v file	Show stats	🟢
--rm	Remove source file after compress	zstd --rm file	Save disk space	🟡
--test	Verify archive integrity	zstd --test file.zst	Validate before restore	🟢
--long	Enable large window (better ratio on large files)	zstd --long=27 file	Huge site archives	🔴
tar -I zstd	Integrate with tar	tar -I zstd -cvf backup.tar.zst dir/	Full WordPress backups	🟡–🔴 (depends level)

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Examples

Basic Compression

zstd-basic-compress.sh

zstd wp-config.php

Output:

example-zstd-basic-compress.txt

wp-config.php.zst : 77.81% compressed (5 KB → 3.9 KB)

Use Case: Light config backup.

CPU Impact: Low.

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Max Compression Level

zstd-max-compress.sh

zstd -19 wpdb.sql

Output:

example-zstd-max-compress.txt

wpdb.sql : 90.2% compressed (120 MB → 11.7 MB)

Use Case: Database archive before transfer.

CPU Impact: High (slower ≈ 3× CPU load).

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Keep Original and Save Elsewhere

zstd-output-to-path.sh

zstd -o /home/wpbackup/db_2025-10-25.sql.zst /home/dev_wpstrategist/db.sql

Output:

example-zstd-output-to-path.txt

/home/wpbackup/db_2025-10-25.sql.zst : 82.1% ratio

Use Case: Store compressed DB in backup folder.

CPU Impact: Moderate.

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Decompress Database

zstd-decompress-file.sh

zstd -d /home/wpbackup/db_2025-10-25.sql.zst

Output:

db_2025-10-25.sql restored OK

Use Case: Prepare restore.

CPU Impact: .

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Full WordPress Backup as .tar.zst

create-wordpress-tar-zst.sh

tar -I zstd -cvf /home/wpbackup/wp_2025-10-25.tar.zst /home/dev_wpstrategist/public_html

Output (snippet):

example-tar-zst-output-snippet.txt

public_html/wp-admin/
public_html/wp-content/
public_html/wp-includes/
Archive size : 450 MB → 95 MB (78.8% ratio)

Use Case: High-speed compressed site backup.

CPU Impact: – (depends level).

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Extract .tar.zst Archive

extract-wordpress-tar-zst.sh

tar -I zstd -xvf /home/wpbackup/wp_2025-10-25.tar.zst -C /home/dev_wpstrategist/public_html

Output:

Files extracted successfully.

Use Case: Restore entire WordPress directory.

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Verify Integrity

zstd-test-integrity.sh

zstd --test /home/wpbackup/db_2025-10-25.sql.zst && echo "OK"

Output:

OK

Use Case: Verify backup not corrupted.

CPU Impact: .

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Check Compression Stats

zstd-verbose-stats.sh

zstd -v /home/wpbackup/db_2025-10-25.sql.zst

Output:

example-zstd-verbose-output.txt

Compressed : 110 MB → 9.8 MB (91.1%)
Compression speed : 280 MB/s  Decompression speed : 900 MB/s

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WordPress VPS use cases

Use Case	Description	Example Command	Benefit
DB Backups	Compress SQL dumps	`mysqldump …	zstd -19 -o …`
Site Files	Full .tar.zst backup	tar -I zstd -cvf backup.tar.zst /var/www/html	Faster transfer
Logs	Rotate & compress logs	zstd --rm /var/log/*.log	Save disk space
Remote Transfer	Pipe via SSH	`tar -I zstd -cvf - dir	ssh …`
Automation	Add to cron	0 2 * * * tar -I zstd …	Daily backups

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Best practices

• Use 19 only for final, non-urgent archives.
• For daily backups, prefer 9 (balance speed vs ratio).
• Always run -test before restoring.
• Combine tar -I zstd to package entire directories.
• Automate cleanup of old archives with find … -delete.
• Monitor CPU usage on VPS to avoid overload.

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Quick lab

1. Export DB

   quick-lab-dump-db.sh

   mysqldump -u root -p wpdb > wpdb.sql
   

2. Compress with zstd

   quick-lab-compress-db.sh

   zstd -9 wpdb.sql
   

3. Verify

   quick-lab-verify-db.sh

   zstd --test wpdb.sql.zst && echo "Backup Valid"
   

4. Restore

   quick-lab-restore-db.sh

   zstd -dc wpdb.sql.zst | mysql -u root -p wpdb
   

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Cheat sheet

zstd-cheat-sheet.sh

zstd file              # Compress file → file.zst
zstd -d file.zst       # Decompress
zstd -# file           # Level (1–19)
zstd -o out.zst in     # Custom output
zstd --test file.zst   # Verify integrity
tar -I zstd -cvf a.tar.zst dir/   # Create archive
tar -I zstd -xvf a.tar.zst -C /target  # Extract archive
zstd -v file           # Show stats
zstd --rm file         # Compress & remove source

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Mini quiz

1. What command integrates zstd with tar?
2. Which option verifies a .zst file’s integrity?
3. What is the maximum compression level available?
4. How would you decompress wp_2025-10-25.tar.zst to /var/www/html/?
5. Which level should you use for daily scheduled backups to balance CPU and speed?

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Restore checklist

Use this checklist before restoring a .tar.zst or .sql.zst backup:

• Verify integrity (zstd --test ...).
• Extract to staging (/tmp/restore-test/).
• Confirm expected content exists (wp-content/uploads/, wp-config.php).

restore-drill-tar-zst.sh

sudo rm -rf /tmp/restore-test
sudo mkdir -p /tmp/restore-test
tar -I zstd -xvf /home/wpbackup/wp_2025-10-25.tar.zst -C /tmp/restore-test

Automation notes

• Avoid very high levels in cron if the VPS is small; start with -3 to -9.
• Consider lowering CPU and I/O priority for scheduled backups.

run-zstd-with-lower-priority.sh

nice -n 10 ionice -c2 -n7 zstd -9 -o /home/wpbackup/db.sql.zst /home/wpbackup/db.sql

warning

Compression is only half the story. A backup you cannot restore quickly is not an operational backup.