Re: recommendations for supported, affordable hardware raid controller.

[Sven Hartge <sven@svenhartge.de>]

Nicholas Geovanis <nickgeovanis@gmail.com> wrote:
> On Sat, Jan 2, 2021, 5:49 AM Sven Hartge <sven@svenhartge.de> wrote:

>> My advise: Don't bother "learning RAID controllers".

> Im afraid I have to agree with this advice. In the presence of
> software like ZFS (from Sun) and LVM (from IBM's AIX), with easy
> availability of NAS, SAN and cloud storage, the arguments in favor of
> hardware RAID local to a server become much thinner. What drives that
> change is the evolution of hardware and networking, not so much the
> software. Both ZFS and LVM are now 20 years old, very mature software.

I see in my environment real RAID controllers only for special systems:

1) standalone ESX servers
2) standalone Windows servers

For ESX servers, as soon as there are 2 or more, they usually are part
of a VSAN (which wants direct access to the disks) or connected to a
proper SAN (mainly NetApp) and boot off of a pair of SD cards or a
BOSS-card containing 2 NVMe modules. (While the latter is kind-of a
RAID controller, it is as simple as they get.)

For Windows servers, the water gets a bit muddles by the existance of
"Storage Spaces", which is more like LVM an Linux, allowing for a
RAID-like usage for every volume created therein.

In that case, the Windows server also gets a very simple RAID controller
or a BOSS card to boot from.

And that is mostly it. Everything else uses MD-RAID and ZFS or uses
object storage provided by (for example) MinIO.

RAID controllers served a purpose when the CPUs were slow, the bandwidth
between the memory, the CPU and the storage was bottlenecked and you
needed a special RAID CPU to offload the needed calculations.

But today: No such thing anymore.

My personal measurements using an LSI card in IR and in IT mode also
confirm this: Using IT mode which just passes the disks through to the
system and using ZFS in RAIDZ2 mode was leaps and bounds faster than the
RAID6 mode native to the controller.

Then add in the faster resilver in case of failure, the ability to
checksum every block and guarantee the correctness of the data and ZFS
wins by a large stretch.

Grüße,
Sven.

-- 
Sigmentation fault. Core dumped.