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neidu3@sh.itjust.works 1 week ago
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.
thallamabond@lemmy.world 1 week ago
Just so I’m clear on this, is “raid controller” a physical device? Real servers are like wizard magic to me.
neidu3@sh.itjust.works 1 week ago
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.