Raid 01
Raid 01
You're encountering an issue where your disk layout is defaulting to a Raid 10 configuration instead of the desired Raid 01 setup. The output shows your SATA devices arranged in a way that favors the SDB array over the MBOARD array. To fix this, you'll need to adjust the order of your devices in the `mdadm` configuration. Consider reordering the arrays so that the MBOARD array comes first, followed by the SATA devices. Also, verify that your `mdadm` command reflects this change to ensure proper initialization for Raid 01.
The choice between raid 01 and raid 10 often depends on your setup. You might have mixed them up, but research suggests raid 10 is usually better. This means you’ll need to assemble the raid 01 manually, whereas madam simplifies it by letting you build a raid 10 all at once.
I noticed you have three 1TB disks and want to combine them into a single 3TB drive. Mdadm usually creates even partitions, but you mentioned wanting to start with a 0 and then build up. Do you know another tool that can help you create a 0+1 partition layout?
I believe RAID 5 could be more suitable for your needs. Based on the setup you mentioned, the system is likely to struggle with buffering all the data after changes on the 3-drive array, even if it's manageable. RAID 1 aims to maintain consistency between disks, so most software will pause changes on the single drive until updates are complete, which restricts performance. At least for writes, this approach works well. RAID 5 distributes parity across all drives, ensuring that a single drive failure doesn’t result in data loss. It would also simplify future additions of drives to the array. I also think it’s important to remember that RAID isn’t a backup solution by itself—misconfigurations can lead to significant data loss. With software RAID, you don’t have to worry about hardware controller failures. Sadly, many of us lack proper data protection measures.
Consider changing the three drives to RAID 0 and then using the fourth drive alone as a backup instead. This way, you avoid risking the loss of 2 TB of space in a RAID 5 setup.
Three of your disks (2.7TB each) will total 8.1TB in raid 0. That means your initial plan... Well, you're right to notice—raid 1 can't be unbalanced because both arrays must match in size. Sorry, I stayed up late. So let's abandon the uneven raid 01 approach. Instead, go with raid 0 plus a backup: three drives in raid 0 give you 8.1TB. Remember, your fourth drive only has 2.7TB available for backups from that fast raid 0 array. If you use four drives in raid 5, the overall size stays at 8.1TB. Raid 5 won't match the speed of raid 10, but it offers more room for growth later. For simple storage needs, raid 5 should suffice. If you're handling large databases or complex data, raid 10 might be the better choice.
Three drives make up one terabyte each. One of them holds three terabytes. If I combine five of them, I’d lose two terabytes on the three-terabyte drive. However, if I use just one drive, I can read and write to the three smaller 1-terabyte drives and then mirror the data across them to reach the capacity of the single drive. It appears mdadm doesn’t support this setup. It seems I can opt for simply saving the mirrored array to one drive that matches the total capacity. This approach requires a bit more automation.
It seems I missed that detail earlier. While hacks for data management aren't my preference, the choice is yours. I suggest using a 6 or 8 TB external drive and setting up both manual and automated backups to it. Leaving your existing drives in JBOD makes sense, as larger external drives are affordable and you could even store one in a dedicated area connected to a Raspberry Pi.