My current home lab had 2x4tb drives in Raid 1. Today’s goal is converting to Raid 5 and adding 4x4tb drives to expand storage without losing data. THIS IS NOT A GUIDE, unless it works.
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Ooh, I did this a while back, except it was Raid5 to Raid6. Turns out one of the servers in a cluster were, for some reason, set up with 11 disks in raid5 + hot spare, except for raid 6 on all raids on all servers. Took me embarrassingly long to realize why storage space was as expected despite one disk being reported as not in an array.
Storcli and a nice raid controller makes thinks like this easy, as long as you grab enough coffee and read the storcli syntax while taking notes to build the full command string.
Just so I’m clear on this, is “raid controller” a physical device? Real servers are like wizard magic to me.
They can be. Some motherboards come with one built in. But in most cases it refers to its own PCIe card, such as one of the many models from LSI Megaraid.
The advantage of this is that it can have a small capacitor bank (or a proper battery) to provide emergency power so that if something stupid happens such as motherboard failure, the raid controller will use this power to cleanly write to the disks.
Here is the tutorial I’m using
https://dev.to/madmannew/how-to-convert-lv-or-md-raid1-and-0-into-raid5-without-losing-data-3mfl
So far I’m about 22% done converting the Raid 1 to Raid 5, looks like it will take around 6 hours.
Anyone else done this? Any pointers?
Have backups for anything you can’t afford to lose, and be patient.
I would recommend move to BTRFS or ZFS. Easyer and safer to work with.
Don’t use the RAID56 functionality of BTRFS, the official docs still list it as unstable. Apart from that it’s pretty good.
Still? Good God, it’s been like 15 years.
Turns out the old gag “You can’t get there from here; You have to go somewhere else and start” is actually true for btrfs’s RAID support.
Agreed. I’m using it as a mirror, and I’ll probably add another mirror once I run out of space.
Bro The RAID Fuckin’ Sucks
ZFS for “RAID” is fine. Btrfs for a single disk (or on top of mdraid or hardware raid) is also fine.
I am running BTRFS Raid 6. i have no problems with it. You need a UPS to avoid transient errors.
You’d be better converting to ZFS or something else rather than just RAID (I’m assuming it is hardware raid) but I bet that has been mentioned a lot
If you’re adding drives with more capacity, why bother converting? Just create the new one, copy the data, then expand over the old disks.
Ok that is why this is not a tutorial. This idea is much better.
