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I don’t see why anyone would ever want to use hardware RAID. It invariably leads to the day when your hardware is busted, there’s no replacement parts, and you

by koolba 6y ago

I don’t see why anyone would ever want to use hardware RAID. It invariably leads to the day when your hardware is busted, there’s no replacement parts, and you can’t read your volumes from any other machine. Use the kernel RAID and you can always rip out disks, replace them, or just boot off a USB stick.

seniorThrowaway 6y ago
Totally agree and I'll go one further, I don't want to use RAID at all in a non professional context. Maybe I'm too simplistic but for my personal stuff I don't use RAID, LVM or anything beyond plain ext4 file systems on whole disks. For redundancy I use rsync at whatever frequency makes sense to another disk of the same size. I've run like this for 10 years and replaced many disks without losing data. The time I ran soft RAID I lost the whole array because one disk failed and a SATA error happened at the same time.
- tialaramex 6y ago
  LVM is very nice because it eliminates that problem where you've got an almost full 2TB disk and you bought another 2TB disk and now you need to figure out what moves where. With LVM you just say nah, that's just 2TB more space for my data, let the machine figure it out. I mean, if you enjoy sorting through going "OK that's photos of my kids, that goes in pile A, but these are materials from the re-mortgage application and go in pile B" then knock yourself out, but I have other things I want to do with my life, leave it to the machine to store stuff. If you lost everything that's because you lacked backups and (repeat after me) RAID is not a backup. Everybody should get into the habit of doing backups. Like any survivalist learns, two is one and one is none.
namibj 6y ago
Because of performance, especially regarding being able to use a battery-backed write-back cache on the controller to give a "safe in the event of powerfailure" confirmation to the application before it actually hits disk/flash. The "can't read from any other machine" is handled by making sure (this includes testing) that the volumes are readable with dmraid. At least that's for SAS/SATA applications. I'm not sure about NVMe, as it uses different paths in the IO subsystem.
- nucleardog 6y ago
  > Because of performance, especially regarding being able to use a battery-backed write-back cache on the controller to give a "safe in the event of powerfailure" confirmation to the application before it actually hits disk/flash. Is this not easily mitigated with a smart UPS? (i.e., one that will notify the host when the battery is low so it can shut down cleanly)
gjs278 6y ago
a lot of hardware raid has been emulated by the linux kernel. you can mount megaraid / lsi raids just fine in software. and there will basically always be replacement parts either way.

by koolba 6y ago

seniorThrowaway 6y ago

Totally agree and I'll go one further, I don't want to use RAID at all in a non professional context. Maybe I'm too simplistic but for my personal stuff I don't use RAID, LVM or anything beyond plain ext4 file systems on whole disks. For redundancy I use rsync at whatever frequency makes sense to another disk of the same size. I've run like this for 10 years and replaced many disks without losing data. The time I ran soft RAID I lost the whole array because one disk failed and a SATA error happened at the same time.

tialaramex 6y ago
LVM is very nice because it eliminates that problem where you've got an almost full 2TB disk and you bought another 2TB disk and now you need to figure out what moves where. With LVM you just say nah, that's just 2TB more space for my data, let the machine figure it out. I mean, if you enjoy sorting through going "OK that's photos of my kids, that goes in pile A, but these are materials from the re-mortgage application and go in pile B" then knock yourself out, but I have other things I want to do with my life, leave it to the machine to store stuff. If you lost everything that's because you lacked backups and (repeat after me) RAID is not a backup. Everybody should get into the habit of doing backups. Like any survivalist learns, two is one and one is none.

namibj 6y ago

Because of performance, especially regarding being able to use a battery-backed write-back cache on the controller to give a "safe in the event of powerfailure" confirmation to the application before it actually hits disk/flash. The "can't read from any other machine" is handled by making sure (this includes testing) that the volumes are readable with dmraid. At least that's for SAS/SATA applications. I'm not sure about NVMe, as it uses different paths in the IO subsystem.

nucleardog 6y ago
> Because of performance, especially regarding being able to use a battery-backed write-back cache on the controller to give a "safe in the event of powerfailure" confirmation to the application before it actually hits disk/flash. Is this not easily mitigated with a smart UPS? (i.e., one that will notify the host when the battery is low so it can shut down cleanly)

gjs278 6y ago

a lot of hardware raid has been emulated by the linux kernel. you can mount megaraid / lsi raids just fine in software. and there will basically always be replacement parts either way.