On Sat, 2020-11-14 at 18:55 +0100, Simon Matter wrote:
> > On Wed, 2020-11-11 at 16:38 -0700, Warren Young wrote:
> > > On Nov 11, 2020, at 2:01 PM, hw <hw@xxxxxxxx> wrote:
> > > > I have yet to see software RAID that doesn't kill the performance.
> > >
> > > When was the last time you tried it?
> >
> > I'm currently using it, and the performance sucks. Perhaps it's
> > not the software itself or the CPU but the on-board controllers
> > or other components being incable handling multiple disks in a
> > software raid. That's something I can't verify.
> >
> > > Why would you expect that a modern 8-core Intel CPU would impede I/O in
> > > any measureable way as compared to the outdated single-core 32-bit RISC
> > > CPU typically found on hardware RAID cards? These are the same CPUs,
> > > mind, that regularly crunch through TLS 1.3 on line-rate fiber Ethernet
> > > links, a much tougher task than mediating spinning disk I/O.
> >
> > It doesn't matter what I expect.
> >
> > > > And where
> > > > do you get cost-efficient cards that can do JBOD?
> > >
> > > $69, 8 SATA/SAS ports: https://www.newegg.com/p/0ZK-08UH-0GWZ1
> >
> > That says it's for HP. So will you still get firmware updates once
> > the warranty is expired? Does it exclusively work with HP hardware?
> >
> > And are these good?
> >
> > > Search for “LSI JBOD” for tons more options. You may have to fiddle
> > > with the firmware to get it to stop trying to do clever RAID stuff,
> > > which lets you do smart RAID stuff like ZFS instead.
> > >
> > > > What has HP been thinking?
> > >
> > > That the hardware vs software RAID argument is over in 2020.
> > >
> >
> > Do you have a reference for that, like a final statement from HP?
> > Did they stop developing RAID controllers, or do they ship their
> > servers now without them and tell customers to use btrfs or mdraid?
>
> HPE and the other large vendors won't tell you directly because they love
> to sell you their outdated SAS/SATA Raid stuff. They were quite slow to
> introduce NVMe storage, be it as PCIe cards or U.2 format, but it's also
> clear to them that NVMe is the future and that it's used with software
> redundancy provided by MDraid, ZFS, Btrfs etc. Just search for HPE's
> 4AA4-7186ENW.pdf file which also mentions it.
>
> In fact local storage was one reason why we turned away from HPE and Dell
> after many years because we just didn't want to invest in outdated
> technology.
>
I'm currently running an mdadm raid-check and two RAID-1 arrays, and the
server shows 2 processes with 24--27% CPU each and two others around 5%.
And you want to tell me that the CPU load is almost non-existent.
I've also constantly seen much better performance with hardware RAID than
with software RAID over the years and ZFS having the worst performance of
anything, even with SSD caches.
It speaks for itself, and, like I said, I have yet to see a software RAID
that doesn't bring the performance down. Show me one that doesn't.
Are there any hardware RAID controllers designed for NVMe storage you could
use to compare software RAID with? Are there any ZFS or btrfs hardware
controllers you could compare with?
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