RAID-Z and Its Difference Between RAID-Z2 vs RAID-Z3
Here you will find out:
- what is RAID-Z
- RAID-Z vs RAID-Z2 vs RAID-Z3
Are you ready? Let's read!
What is RAID-Z?
This is a non-standard RAID that uses the ZFS file system; no other file system can be used for this array. Note that there is not a single hardware controller that implements RAID-Z.
The ZFS file system uses an additional level of checksums to search for data corruption without displaying the appropriate messages. ZFS uses checksums with any level of redundancy, including single disk pools. The distribution mechanism is similar to RAID 5, but it uses dynamic bandwidth. Any block, regardless of its size, has its own RAID bandwidth, which means that each RAID-Z record is a full-band record.
In addition, this array has very high performance and speed, even better than RAID 5 in this regard.
Self-healing RAID-Z
The self-healing data function is very interesting and useful. It works as follows. When a RAID-Z block is read, the ZFS file system compares this block with the checksum. If the result of this comparison is unsatisfactory, then ZFS reads the parity information and checks which drive returned the wrong data.
After that, the damaged information is automatically restored and returned to the right place.
RAID-Z vs RAID-Z2 vs RAID-Z3
In RAID-Z, files are never divided exactly in half, but the data is treated as blocks of a fixed length. The minimum number of disks you can use is three. Three drives are usually combined into a virtual device (vdev).
RAID-Z (sometimes called RAID-Z1) will provide a record of each unique data block so that it can recover from the failure of any single disk on vdev. In this case, the data is automatically distributed across the disk in the most optimal way. RAID-Z1 is practically an analogue of RAID 5, as it uses single parity. It is not difficult to guess that fault tolerance will be the same; i.e., there may be a possible failure of a drive.
RAID-Z2 is more fault-tolerant, as it uses two parity blocks and two data blocks from one piece of information. This is an analogue of RAID 6 and can also withstand the collapse of as many as two disks. In RAID-Z2, the maximum number of disks is at least four.
You can go further and try RAID-Z3, which has a maximum of at least five disks and the ability to survive damage to up to three disks. RAID-Z3 is rarely used due to its size. It is also not as space-efficient as other RAID-Z options.
Data recovery from RAID-Z
Disk failure can occur in several ways:
- When a disk is completely damaged or you get messages that certain sectors are damaged
- When data is corrupted without any warning
In the first case, RAID-Z can, when it is known which block or sector is damaged, independently reconstruct the data.
When a disk is completely damaged, this array behaves like a traditional one. That is, it is clear that all sectors are damaged and should be restored.
When dealing with noiseless data corruption, RAID-Z can help you recover it with the extra checksum provided by ZFS.
If automatic data recovery has not occurred or is simply not possible, you should consider a special RAID recovery application. Users of DiskInternals RAID Recovery application unanimously say that this is a great software solution, since the recovery results are stunning!
The utility supports both manual and fully automatic determination of the main parameters of the array (array type, RAID controller type, strip size and disk order, etc.). It then automatically restores the data. All this is possible thanks to the Recovery Wizard, who will support you at each step of the process. In addition, the preview of the results will please everyone, since it is free of charge and only after you get it do you need to decide whether to purchase a license or not. Learn more about RAID 2 vs RAID 3.
Good luck!