# RocksDB Compression in Ceph: Space Savings with No Performance Cost

DevFeed: [RocksDB Compression in Ceph: Space Savings with No Performance Cost](<https://devfeed.tech/articles/rocksdb-compression-in-ceph-space-savings-with-no-performance-cost-12328.md>)

Original publisher: [Read original article](<https://ceph.io/en/news/blog/2025/rocksdb-compression-ftw/>)

Author: Daniel Alexander Parkes, Anthony D'Atri

Published: 2025-12-17T00:00:00Z

Content type: article

Language: en

Sources: [Ceph Blog](<https://devfeed.tech/sources/ceph-blog.md>)

Topics: [Compression](<https://devfeed.tech/topics/compression.md>), [Database](<https://devfeed.tech/topics/database.md>), [Hardware](<https://devfeed.tech/topics/hardware.md>), [ibm](<https://devfeed.tech/topics/ibm.md>)

Tags: [blog-post](<https://devfeed.tech/tags/blog-post.md>), [ceph](<https://devfeed.tech/tags/ceph.md>), [compression](<https://devfeed.tech/tags/compression.md>), [configuration](<https://devfeed.tech/tags/configuration.md>), [cost](<https://devfeed.tech/tags/cost.md>), [devices](<https://devfeed.tech/tags/devices.md>), [en-article](<https://devfeed.tech/tags/en-article.md>), [en-blog-post](<https://devfeed.tech/tags/en-blog-post.md>), [ibm](<https://devfeed.tech/tags/ibm.md>), [mon](<https://devfeed.tech/tags/mon.md>), [nvme](<https://devfeed.tech/tags/nvme.md>), [osd](<https://devfeed.tech/tags/osd.md>), [performance](<https://devfeed.tech/tags/performance.md>), [rados](<https://devfeed.tech/tags/rados.md>), [reef](<https://devfeed.tech/tags/reef.md>), [rocksdb](<https://devfeed.tech/tags/rocksdb.md>), [space](<https://devfeed.tech/tags/space.md>), [storage](<https://devfeed.tech/tags/storage.md>)

## AI overview

This article reports Ceph performance tests showing that enabling RocksDB compression can substantially reduce metadata database space, especially for smaller objects, without harming throughput or resource consumption. The tests used IBM Storage Ceph 7.1 with BlueStore OSDs, HDD object storage, and NVMe devices for the RocksDB WAL and database.

## Source excerpt

Introduction ¶ In the world of data storage, engineers and architects constantly face a fundamental dilemma: the trade-off between performance and efficiency. It's a balancing act. When you want to save space, you typically enable features like compression, but the common assumption is that this will cost you performance, a CPU cycle tax that slows throughput. But what if you could significantly reduce your metadata storage footprint without slowing things down? This search for an answer to this question started with research work from Mark Nelson, who published a blog post on ceph.io that covers RocksDB tuning in depth, exploring RocksDB compression with positive results. These promising results sparked a conversation on the upstream GitHub about enabling compression by default; a link to the PR is available here. To build on the previous investigation, the Ceph performance team ran tests on a robust hardware configuration running IBM Storage Ceph 7.1 (Reef). The cluster used the BlueStore OSDs for an erasure-coded (EC 4+2) pool, with a hybrid OSD storage setup: HDDs for object data and fast NVMe drives for the BlueStore WAL+DB. To understand the test, it's helpful to know what the WAL+DB is. In modern Ceph, the BlueStore storage engine manages all data on the OSDs (physical devices). To do this, it must maintain a vast catalog of internal metadata: think of it as a high-speed index that quickly locates every piece of data. RocksDB, a high-performance key-value database, manages this critical index. In our hybrid cluster, the RocksDB database runs on the fast NVMe deviceses, while the actual object data resides on the slower HDDs. Because this metadata can grow very large, RocksDB's efficiency, how much space it consumes on those expensive NVMe drives, is a critical factor in the cluster's overall cost and performance. Our test, therefore, focuses on a simple, high-stakes question: Can we compress this metadata to save space without paying a performance penalty? Ex