Re: raid10 is killing me, and applications that aren't willing towait for it to respond

[David Christensen <dpchrist@holgerdanske.com>]

On 12/13/23 15:33, gene heskett wrote:
> 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


Thank you for providing a console session that confirms the issue is not 
md RAID.


For completeness, I suggest that you do both write and read benchmarks:

2023-12-13 17:56:58 root@taz ~
# smartctl -i /dev/sda | grep "Device Model"
Device Model:     INTEL SSDSC2CW060A3

2023-12-13 17:57:12 root@taz ~
# dd if=/dev/zero of=/home/dpchrist/100mb.zero bs=1M count=100 oflag=sync
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 1.6329 s, 64.2 MB/s

2023-12-13 17:57:57 root@taz ~
# free && sync && echo 3 > /proc/sys/vm/drop_caches && free
               total        used        free      shared  buff/cache 
available
Mem:        32698252     1941032    29428472      761160     1328748 
29606508
Swap:         976892           0      976892
               total        used        free      shared  buff/cache 
available
Mem:        32698252     1941516    29580404      717360     1176332 
29650836
Swap:         976892           0      976892

2023-12-13 17:58:03 root@taz ~
# dd of=/dev/null if=/home/dpchrist/100mb.zero bs=1M count=100 oflag=sync
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 0.263723 s, 398 MB/s


I have found that as I run computers, there is an accumulation of cruft 
over time.  The more I mess with a computer, the sooner it becomes 
unstable.   Eventually, "finding the needle in the haystack" and 
"putting Humpty Dumpty back together again" do not work -- the computer 
requires a backup-wipe-install-restore cycle.  Your posts indicate that 
your computer is overdue.


And, I suspect a deeper issue -- you have one computer that is your 
workstation, your file server, and your backup server.  This 
over-complicates everything and creates a strong disincentive to 
backup-wipe-install-restore.  I have been there, done that, lost 
service, and lost data.  Now I have several laptops/ desktops/ 
workstations, a dedicated file server, and a dedicated backup server. 
Life is good.  :-)


Again -- I suggest that you build a backup server, then build a file 
server, then rebuild the workstation.  I am confident you will be 
rewarded with simpler administration and improved reliability.


David