Re: raid10 is killing me, and applications that aren't willing towait for it to respond
On 12/13/23 16:30, Andy Smith wrote:
Hello,
On Wed, Dec 13, 2023 at 10:26:19AM -0500, gene heskett wrote:
I thought I was doing things right a year back when I built a raid10 for my
/home partition. but I'm tired of fighting with it for access. Anything that
wants to open a file on it, is subjected to a freeze of at least 30 seconds
BEFORE the file requester is drawn on screen.
I haven't chimed in to any of the multiple times you've brought this
to the list, because it's just so bizarre. I've about 20 years'
experience of using mdadm and have never seen anything like what
you're reporting, so I just don't know what the problem could be or
how to find it.
The only times I've seen anything remotely like it have been when
there's been hardware problems with failing writes, but I know
you've been through this with the list several time sand no such low
level issues were ever uncovered.
Would it be correct to say that you only experience these IO delays
from GUI applications? Like, if you do a simple:
$ time echo "test" > ~/foo
does that complete in a normal time?
The lshw >lshw.txt would be in the "guiless" category, and it worked
even quicker than if I left it to come out on the cli. Another item that
may be of interest is that the gui is xfce4.
That was a bit over a 40k write
And if you did a bigger write, again from the command line?
$ dd if=/dev/zero of=/path/to/your/home/dir/zero bs=1m count=100
00+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 0.0783268 s, 1.3 GB/s
I had to use an uppercase M in the bs=, to get:
gene@coyote:~$ time dd if=/dev/zero of=/home/gene/zero bs=1M count=100
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 0.0829926 s, 1.3 GB/s
real 0m0.085s
user 0m0.005s
sys 0m0.080s
I'd have to say thats realtime. no lag.
and with sync:
$ dd if=/dev/zero of=/path/to/your/home/dir/zero bs=1m count=100 oflag=sync
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 0.463356 s, 226 MB/s
gene@coyote:~$ time dd if=/dev/zero of=/home/gene/zero bs=1M count=100
oflag=sync
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 0.935655 s, 112 MB/s
real 0m0.940s
user 0m0.000s
sys 0m0.254s
A lot slower but still no lag, about an even second.
But then when you try to use some GUI application to save something
to a file, the initial save file dialog takers ages to appear and
everything seems frozen?
Correct...
If so then I feel like this may actually be some sort of problem
with your desktop environment, but then I've no idea how to narrow
that down.
I think we have made progress, Andy, having narrowed it down to the gui.
To me that is progress. Now I need a gui expert, which I am for sure
not. Never have been, never will be.
Thanks,
Andy
Thanks a bunch Andy, I think your logic was quite helpful in narrowing
down the problem area.
Take care, stay warm and well.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
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