Guide: RAID-Z Technology
In this article you will find out:
- how to work with RAID-Z Technology
- how to protect your data
Are you ready? Let's read!
RAID is a redundant array of independent disks. This storage mechanism makes it possible to recover data even in the event of a disk failure. There are several array levels (RAID 0, RAID 1, etc.) depending on how the data is distributed across the disks. This article will focus on the OpenZFS - specific RAID-Z.
RAID-Z is not a copy of data to a spare drive. Multiple disks configured in RAID simultaneously write data with all disks active and online. In other words, backups are copies of data that are created from time to time, while RAID is constantly backing up in real time.
RAID-Z and Its Variations
At least 3 are required to create a RAID-Z, and the storage vendor can also be network-attached storage, virtual block device, etc.
So, to keep it simple, let's focus on three disks of the same size and start building the RAID-Z1.
These disks can be combined into a virtual device (1 vdev) in your zpool. For example, you want to store a 1 GB file in this pool. The array then splits it into two equal 512 MB chunks and then generates a third 512 MB chunk (called a parity block). These three blocks are written into three separate vdev files and the file takes up a total of 1.5 GB of space.
In this case, if one of the disks fails and the first fragment is lost, then the second fragment and the parity block can be used to recreate the first. Bottom line: you don't have to worry about a single disk failure, but your files will use 50% more space.
If you need more space, you can add a vdev and that way you can add disks in sets of three and treat each new set as one logical vdev.
You don't have to worry about one disk failure in this new vdev and one disk failure in the older one. But if multiple disks fail in one vdev, data recovery will be impossible.
You can upgrade to RAID-Z2 if the array's resistance to loss of one disk is not enough for you. The operation of RAID-Z2 is similar to the operation of RAID-Z1, but it creates two parity blocks and two data blocks from one piece of information. This way you can handle up to 2 disk failures per vdev. Note that vdev must have at least 4 disks to configure RAID-Z2.
Likewise, configuring a RAID-Z3 requires at least 5 disks and can withstand failure of 3 of them.
It should be concluded that RAID-Z3 costs more than RAID-Z2, which in turn is not as efficient in terms of space utilization as RAID-Z1.
Protect Your Data!
Since modern arrays can have multiple drives, simultaneous or sequential failure of two or more drives does not seem so unlikely. Therefore, when working with any array, including RAID-Z3, RAID-Z2, RAID-Z1, etc., you should have decent data recovery software when needed. This is exactly what DiskInternals RAID Recovery does. It recovers the maximum amount of data in any format from damaged arrays. The utility finds and retrieves information from Linux, NAS, macOS, and UNIX RAID systems. If necessary, it will help you create a disk image for free for each client. There is a free preview function to visually check files for integrity and quality.
Here are the instructions on how to use DiskInternals RAID Recovery so that all recovery steps are clear:
First, download and install the application on your computer.
Next, open the program and select the Wizard, which will make the process easier and clearer.
Select the array to scan and click the Scan button (for quick or full recovery). After a certain period of time, you will see the search results on the monitor screen.
All files found, without exception, can be viewed for free, just like any other DiskInternals application.
After that, when you are sure of the results, buy a license and export the data to any storage device.
This procedure is fast and fun because in a few minutes seemingly irretrievably lost files will be returned to you.
Good luck, you will succeed 100%!