4 ms·

I was under the impression that hardware RAID is generally considered unreliable.

oneplane 3y ago
Hardware RAID is pretty much a niche at this stage. And unreliable and unsafe in general. Using it is like having an open fire pit inside your home because it's nice and cozy, and assuming that your house not having burned down yet means it's a good idea. So far the only deployments where I've still seen it somewhat relevant is single-node Windows machines without virtualisation (so the balance between trusting windows with your block storage vs. trusting a RAID controller swings towards the controller), and large proprietary SANs where you don't really have a choice. Everything else is either local software RAID (or ZFS), or a cluster filesystem with block storage support for SAN consumption. And then there is the worst of all worlds: firmware-enabled software RAID like the ones you get with consumer mainboards. As far as I know, that only exists because of windows and the legacy inability to boot from anything except a single-disk magic method on MBR or single ESP partition based booting in UEFI. It's all just crutches for bad systems to not have to do it correctly.
- justsomehnguy 3y ago
  > So far the only deployments where I've still seen it somewhat relevant I'm glad what all your deployments have a competent sysadmins supervisng them. Sadly, this is not how it works in the real life, so I doubt your experience cover 100% of use cases.
Volundr 3y ago
It's complicated. For consumer level users I'd recommend software RAID because knowing what your getting with hardware RAID is tricky. If your motherboard offers a built-in RAID it's almost certainly crap and your better off disabling it first thing. In general these aren't actually hardware RAIDs anyway, it's actually implemented in the drivers. Low end RAID cards are sometimes better, but mdraid or windows RAID will still probably be more reliable. It's really only expensive enterprise-grade RAID cards that meaningfully compete with software RAID and you'll want to look at the tradeoffs of each.
jeffbee 3y ago
Hardware RAID is now almost universal, we just call it "SSDs". With an SSD the relationship between the kernel's block device abstraction and the reality of how the blocks are stored has been interdicted by an opaque controller that decides what blocks to write, how to exploit device parallelism, and what mathematical codes to use for redundancy.
- ilyt 3y ago
  Uh, no. Main purpose for RAID is device failure prevention, SSDs do nothing to address that as controller managing storage chips can still fail, or go "well, one of chips is dead, you're not getting your data back".
ilyt 3y ago
It's generally PITA, as you need to use a piece of proprietary software to manage, and often have more limitations than mdadm when it comes to what is possible and migration between RAID levels.

Hardware RAID is pretty much a niche at this stage. And unreliable and unsafe in general. Using it is like having an open fire pit inside your home because it's nice and cozy, and assuming that your house not having burned down yet means it's a good idea. So far the only deployments where I've still seen it somewhat relevant is single-node Windows machines without virtualisation (so the balance between trusting windows with your block storage vs. trusting a RAID controller swings towards the controller), and large proprietary SANs where you don't really have a choice. Everything else is either local software RAID (or ZFS), or a cluster filesystem with block storage support for SAN consumption. And then there is the worst of all worlds: firmware-enabled software RAID like the ones you get with consumer mainboards. As far as I know, that only exists because of windows and the legacy inability to boot from anything except a single-disk magic method on MBR or single ESP partition based booting in UEFI. It's all just crutches for bad systems to not have to do it correctly.

justsomehnguy 3y ago
> So far the only deployments where I've still seen it somewhat relevant I'm glad what all your deployments have a competent sysadmins supervisng them. Sadly, this is not how it works in the real life, so I doubt your experience cover 100% of use cases.

Volundr 3y ago

It's complicated. For consumer level users I'd recommend software RAID because knowing what your getting with hardware RAID is tricky. If your motherboard offers a built-in RAID it's almost certainly crap and your better off disabling it first thing. In general these aren't actually hardware RAIDs anyway, it's actually implemented in the drivers. Low end RAID cards are sometimes better, but mdraid or windows RAID will still probably be more reliable. It's really only expensive enterprise-grade RAID cards that meaningfully compete with software RAID and you'll want to look at the tradeoffs of each.

jeffbee 3y ago

Hardware RAID is now almost universal, we just call it "SSDs". With an SSD the relationship between the kernel's block device abstraction and the reality of how the blocks are stored has been interdicted by an opaque controller that decides what blocks to write, how to exploit device parallelism, and what mathematical codes to use for redundancy.

ilyt 3y ago
Uh, no. Main purpose for RAID is device failure prevention, SSDs do nothing to address that as controller managing storage chips can still fail, or go "well, one of chips is dead, you're not getting your data back".

ilyt 3y ago

It's generally PITA, as you need to use a piece of proprietary software to manage, and often have more limitations than mdadm when it comes to what is possible and migration between RAID levels.