Is it performance, redundancy or storage efficiency? In other words, do you need speed, safety or the most space possible? This post will briefly describe common configurations and how each can meet the criteria mentioned above.
For other implementations, such ZFS RAID, the majority of this post will hold true; however, there are some differences when you dig into the details. These will be addressed in a post to come! Typically, a RAID 0 is not used alone in production environments, as the risk of data loss usually trumps the speed and storage benefits. RAID 1 gives you peace of mind knowing that you always have a complete copy of your data disk should one fail, and short rebuild times if one ever does.
In fact, there is even a small write penalty as every time something needs to be written to the array, it has to write it twice, once to both disks. This has the benefit of striped read performance and redundancy, meaning you can lose up to 2 disks in the array and still be able to rebuild lost data. This write penalty arises from the way the data and parity is laid out across the disks. RAID 3 Striped set with dedicated parity Data is split evenly between two or more disks, plus a dedicated drive for parity storage.
Poor performance for multiple simultaneous instructions. A single drive failure will rebuild. Parity is split between disks. Large size, fast speed, and redundancy. The total array size is reduced by parity. No parity. Only one drive in a mirrored set can fail. Without RAID installed, your server and business will suffer downtime while the drive is being reconfigured and replaced. Then backups need to be restored; all this could take 5 or more hours easy.
With RAID installed, the drive would be replaced, and you could rebuild and sync the RAID from the old drive to the new drive, and there would also be no backup restoration required. This provides optimal performance, as the processing is handled by the RAID card rather than the server, providing less strain when writing backups and restoring data.
This is the cheaper option; all you need to do is connect the drives and configure the OS. Here is a very simple TLDR chart. Read on for a more detailed version of the pros and cons of each. Your dedicated server loses power before changes have left the cache and committed to disk, resulting in corrupted data. The contents on the RAID card become unrecoverable and you may not know what files are damaged. This, combined with backups and copies in other datacenters, is how archive services like AWS Glacier and Backblaze achieve RAID 10 requires at least four drives, and also requires an even number of total drives.
This gives you all the benefits of RAID 1 and RAID 0 without many downsides—fast read speeds, fast write speeds, high redundancy, and easy rebuilds, while still being able to use half of the total space of all of your drives.
In the diagram above, Disk 1 and Disk 3 could fail, and the array could still be fully rebuilt though if both Disk 0 and Disk 1 fail, that array is unrecoverable.
This improves performance just like RAID 10, most importantly improving write performance, since reading from the other drives when calculating parity is faster. The above article may contain affiliate links, which help support CloudSavvy IT.
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