Re: raid10 is killing me, and applications that aren't willing towait for it to respond
On 12/14/23 00:39, tomas@tuxteam.de wrote:
On Wed, Dec 13, 2023 at 10:26:19AM -0500, gene heskett wrote:
Greetings all;
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. Once it has done the screen
draw and the path is established, read/writes then proceed at multi-gigabyte
speeds just like it should [...]
- disk access latency
- digikam
- photo volume monitor
- cache buffers (which?)
- klipper
I've been here several times with this problem without any constructive
responses [...]
So one more time: Why can't I use my software raid10 on 4 1T SSD's ?????
Gene, just a humble suggestion. I'm too short in time to wade through all
this deep software cake, of which I know but a fraction.
Perhaps if you structured your requests a bit better, the quality of the
answers would improve?
The latest info is that non-gui stuff works instantly. gui stuff lags at
least 30 seconds, mouse still moves but the rest of the same screen is
non-responsive until this tomeout has taken place, then everything
returns to normal.
I've skimmed some of the answers, and they correspond to your confusing
request. Someone mentions DNS timeouts to rule them out right away (do
you access your RAID over the net? Is DNS resolution involved at all?)
no
Other answers veer of in similar disparate directions, but that corresponds
to your request's deeply confusing nature.
Because I was not able to define it any better.
Let me humbly suggest to structure your search a bit (you do have deep
experience in fault searching, we all know).
What I get from your post is that you seem to see the root of your problems
in a long latency on (first?) storage access to your block device (whether
it matters that it be a RAID10 or a RAID42 we just don't know!).
As I also don't know, this raid10 is my only experience with a raid of
any kind.
This looks like a promising avenue, so let's pretend we start with this
one.
Do you experience this latency also with simpler tools (something which
doesn't "draw a requester on screen", like, say, ls or find)?
no, even a dd write is essentially instant.
Let's thus try to rule out the deep pie of sh*** (uh, software stack)
you are using to access the disk. Do you still observe this latency?
Is there a pattern (like, when accessing something for the first time,
and/or accessing things after a longer inactivity period, yadda, yadda).
It repeats per gui access. Starting a gfx program such as OpenSCAD, or
qidislicer from an xfce4 terminal cli, is delayed for this similar but
not always identical lag. And reports odd warnings etc while its getting
ready to open its gui.
Might there be a clue there? IDK I could copy/paste some of it if you
like to see it, but to me it doesn't look related or I would have already.
If yes, you can follow the path "disk access latency". If no, the problem
might lie further up the stack (and then, things like DNS latencies might
play a role again!).
With your posts, my head spins and my time slot in the mornings, before
I go to $DAYJOB is used up before I can start even to think about how
debug things.
And I appreciate that Tomas, $DAYJOBS take precedence, always. Triply
appreciated when you are the only tech person responsible for keeping a
tv station on the air and working smoothly like I was for nearly 50
years before I retired, its not a $DAYJOB, its a $24/7/365.25JOB.
In one short word: please focus. Debugging complex stuff becomes impossible
otherwise.
I now think I have a gui problem and can imagine something in the
original debian gnome install getting the request to open the gui and
has to fail before xfce4 even gets the request. Whether that is true or
not, is up to ways to test the theory. That I'm clueless about. There
is enough kde/plasma installed that it thinks it has to start kmail at
boot time, lots of kde and gnome leftovers, but the popups asking for a
pw, are also subjected to this delay after the bootup is completed. Is
this all connected? At this time IDK.
Cheers
Thank you Tomas.
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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