datapioneer
Blogging about Linux & Other Things
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Zettabyte File System Explained

In this article, I will strive to answer many questions that have been asked about ZFS, such as what is it, why should I use it, what can I do with it, and the like? Let's begin:

Designating Hot Spares in Your ZFS Storage Pool

There is a feature built into ZFS called the "hotspares" feature which allows a sysadmin to identify those drives available as spares which can be swapped out in the event of a drive failure in a storage pool. If an appropriate flag is set in the feature, the "hot spare" drive can even be swapped automatically to replace the failed drive. Or, alternatively, a spare drive can be swapped manually if the sysadmin detects a failing drive that is reported as irreparable.

Setting Up Quotas & Reservations in OpenZFS in Linux

ZFS supports quotas and reservations at the filesystem level. Quotas in ZFS set limits on the amount of space that a ZFS filesystem can use. Reservations in ZFS are used to guarantee a certain amount of space is available to the filesystem for use for apps and other objects in ZFS. Both quotas and reservations apply to the dataset the limits are set on and any descendants of that dataset.

Logs Mirror, Cache, & Snapshots in OpenZFS Filesystem on Linux

Another big advantage to installing ZoL or OpenZFS filesystem on Linux is that as the sysadmin you can create a mirror of two SCSI drives in the filesystem containing your system logs and create a cache consisting of two SSD drives in the filesystem containing system cache information. The logs mirror helps to balance the load of the ZFS pool in the system and also helps to ensure that your log files are preserved in the event of RAIDZ failure. The cache is a part of the ARC (Adaptive Replacement Cache) system in OpenZFS and assists in rebuilding drives to restore your system if drives begin to fail. Read cache is referred to as L2ARC (Level 2 Adaptive Replacement Cache), synchronous write cache is ZIL (ZFS Intent Log), SLOG (Separate Log Device).

Investigating RAIDZ in Debian 10 "Buster" Linux

Now that we have looked at implementing OpenZFS on Linux in Debian 10 Linux and created zfs pool mirrors using OpenZFS as well as created and accessed ZFS datasets on the system, let's turn our attention to implementing RAID in OpenZFS. How does implementing RAID in OpenZFS compare to traditional RAID solutions? Is there a one-to-one correlation between RAIDZ and traditional RAID? Are there advantages to running RAIDZ rather than the traditional RAID solutions?