How does ZFS dedup work?
For deduplication to work, ZFS must keep track of the data blocks stored on your ZFS pool/filesystem. To do that, ZFS creates a deduplication table (DDT) in the memory (RAM) of your computer and store hashed data blocks of your ZFS pool/filesystem there.
How much RAM do I need for deduplication?
Optimally, Data Deduplication should have 1 GB of memory for every 1 TB of logical data. For instance, if you are optimizing a 10 TB volume, you would optimally need 10 GB of memory allocated for Data Deduplication ( 1 GB * 10 ). This ratio will ensure the maximum performance for Data Deduplication jobs.
How do I check my dedup ZFS?
You can use the zfs get command to determine if the dedup property is set. The DEDUP column indicates how much deduplication has occurred. If the dedup property is not enabled on any dataset or if the dedup property was just enabled on the dataset, the DEDUP ratio is 1.00x.
Why does ZFS use so much RAM?
ZFS uses RAM mostly for aggressive caching to cover over both spinning disks and the iops tradeoff vdevs make over traditional raid arrays. Thus low memory is not such a big deal if you have a pool with a single SSD or NVMe device.
How much RAM do I need for ZFS deduplication?
For every TB of pool data, you should expect 5 GB of dedup table data, assuming an average block size of 64K. This means you should plan for at least 20GB of system RAM per TB of pool data, if you want to keep the dedup table in RAM, plus any extra memory for other metadata, plus an extra GB for the OS.
Does TrueNAS scale use ZFS?
TrueNAS® SCALE is an Open Source Hyperconverged Infrastructure (HCI) solution. Built on TrueNAS CORE, SCALE adds Linux Containers, VMs (KVM), and scale-out ZFS storage capabilities.
Is TrueNAS a core or scale?
TrueNAS Scale v. TrueNAS Scale feels like TrueNAS Core, but with better virtualization and Kubernetes support. It feels like it grew up as a NAS and then added features more in-line with some of what Synology and QNAP offer, with a critical difference: there is the promise of scale-out using Gluster and ZFS.
How much RAM do I need ZFS?
ZFS on FreeNAS typically requires a base 8GB plus an additional 1GB per TB of disk space to get “decent” performance. This softens a bit as the number of TB managed gets out past maybe 20 or so. But some more demanding workloads will require substantially more RAM.
How often should you ZFS scrub?
It’s best practice to schedule at least one scrub a month, and some may want to do it as often is even one time a week, although this isn’t completely necessary.
Does ZFS protect bit rot?
raid – ZFS protection against bit rot and silent corruption without RAIDZ – Server Fault.
Can you defrag ZFS?
This is not something you need to so often. Mainly because there’s no notion of online defragmentation in ZFS. That’s really only possible by copying the pool data to another pool or rewriting to new storage.