![]() Finally, you can send the parent data set to its backup target, including the -redact redaction_bookmark argument-and this replicates the nonsensitive blocks only to the backup target. ![]() Then, you create a bookmark on the parent data set, which marks the blocks which changed from the parent to the clone. Next, you delete the sensitive data from the clone. Let's say there are portions of your data that you don't want to back up using ZFS replication. ZFS users are broadly accustomed to seeing lz4 compression accelerate workloads in the real world, not slow them down! Redacted replication In practice, most CPUs can run rings around most storage media (even relatively slow CPUs and fast SSDs). Keep in mind, the throughput "penalties" described assume negligible bottlenecking on the storage medium itself. On the decompression (disk read) side, the throughput penalty is slightly higher, at around 36 percent. During compression (disk writes), zstd-2 is more efficient than even gzip-9 while maintaining high throughput.Ĭompared to lz4, zstd-2 achieves 50 percent higher compression in return for a 30 percent throughput penalty. These graphs are a bit difficult to follow-but essentially, they show zstd achieving its goals. OpenZFS 2.0.0 brings support for zstd-an algorithm designed by Yann Collet (the author of lz4) which aims to provide compression similar to gzip, with CPU load similar to lz4. Traditionally, the algorithm most commonly used has been lz4, a streaming algorithm offering relatively poor compress ratio but very light CPU loading. OpenZFS offers transparent inline compression, controllable at per-data-set granularity. This new feature allows data in the L2ARC to remain available and viable between pool import/export cycles (including system reboots), greatly increasing the potential value of the L2ARC device. Historically, one of the biggest issues with L2ARC is that although the underlying SSD is persistent, the L2ARC itself is not-it becomes empty on each reboot (or export and import of the pool). Systems with very large, very hot working sets can also implement an SSD-based read cache called L2ARC, which populates itself from blocks in the ARC nearing eviction. One of ZFS' most compelling features is its advanced read cache, known as the ARC. With sequential resilvering, ZFS gets the best of both worlds: largely sequential access while still skipping unused portions of the disk(s) involved. But this process involved an abundance of random I/O-so on more nearly full arrays, conventional RAID's more pedestrian block-by-block whole-disk rebuild went much faster. On nearly empty arrays, the ZFS rebuild-known as "resilvering"-was much faster because ZFS only needs to touch the used portion of the disk rather than cloning each sector across the entire drive. Rebuilding degraded arrays in ZFS has historically been very different from conventional RAID. "Far beyond the beaten trail" is not a phrase one should generally apply to the file system that holds one's precious data! Advertisement OpenZFS 2.0.0 modules can be built from source for Linux kernels from 3.10-5.9-but most users should stick to getting prebuilt modules from distributions or well-established developers. ![]() For Ubuntu users who are willing to live on the edge, the popular but third-party and individually maintained jonathonf PPA might make it available considerably sooner. Users of the better-supported but slower-moving Ubuntu probably won't see OpenZFS 2.0.0 until Ubuntu 21.10, nearly a year from now. Users of Linux distributions that use DKMS-built OpenZFS kernel modules will tend to get the new release rather quickly. On Linux, the situation is a bit more uncertain and depends largely on the Linux distro in play. The new OpenZFS 2.0.0 release is already available on FreeBSD, where it can be installed from ports (overriding the base system ZFS) on FreeBSD 12 systems and will be the base FreeBSD version in the upcoming FreeBSD 13. This move has been a long time coming-the FreeBSD community laid out its side of the roadmap two years ago-but this is the release that makes it official. ![]() Along with quite a lot of new features, the announcement brings an end to the former distinction between "ZFS on Linux" and ZFS elsewhere (for example, on FreeBSD). This Monday, ZFS on Linux lead developer Brian Behlendorf published the OpenZFS 2.0.0 release to GitHub. ![]()
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