Re: 5.1.21 Dell 2950 terrible swraid5 I/O performance with swraid on top of Perc 5/i raid0/jbod

[Marc MERLIN <marc@merlins.org>]

On Mon, Aug 19, 2019 at 07:05:42PM +0200, Paolo Valente wrote:
> > newmagic:~# hdparm -t /dev/md2
> > /dev/md2:
> > HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
> >  Timing buffered disk reads:   2 MB in  5.76 seconds = 355.42 kB/sec
> > 
> > I think things hang a bit less, which I suppose it good, but the system is
> > still unusable overall.
> 
> Ok, I'm sorry it didn't help.  Unless someone spots the problem
> somewhere outside BFQ, I'm willing to analyze this apparently tough
> scenario, as an opportunity to improve BFQ.  If fine for you, just
> contact me offline.

I'm sure there is something very wrong somewhere, and that it's not BFQ's
fault. I just haven't been able to pinpoint the problem.

I ended up finding an H700 card with cables that should fit, so I'm going to
try this first, and see what happens, thanks o1bigtenor for the suggestion.

Linux-raid folks, the original post still has a warning likely worth looking
into:
[14852.341924] WARNING: CPU: 0 PID: 2530 at drivers/md/md.c:8180 md_write_inc+0x15/0x40 [md_mod]
which in turn put the array in dirty mode.

Best,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/