start mariadb server problem on external HD - linux

Question

I'm trying to start a local mariadb server on my raspberry pi. I've changed the datadir to point to an external harddrive, and i've gotten that working previously (with other pi's).
however, now when i use this particular pi and type in
sudo service mariadb start
I get
Job for mariadb.service failed because the control process exited with error code.
See "systemctl status mariadb.service" and "journalctl -xe" for details.
When i check journalctl -xe i get
-- The unit mariadb.service has entered the 'failed' state with result 'exit-cod
Oct 07 09:08:25 BLUE systemd[1]: Failed to start MariaDB 10.3.15 database server
-- Subject: A start job for unit mariadb.service has failed
Pokiing around further I find that my ib_buffer_pool in the directory I've specified for this server seems maybe corrupted?
Typing in ls-l for this particlar datadir I get
ls: cannot access 'ib_buffer_pool': Bad message
total 110628
-rwxrwxrwx 1 pi pi 16384 Oct 7 08:34 aria_log.00000001
-rwxrwxrwx 1 pi pi 52 Oct 7 08:34 aria_log_control
-rwxrwxrwx 1 pi pi 0 Jul 1 06:34 debian-10.3.flag
-????????? ? ? ? ? ? ib_buffer_pool
-rwxrwxrwx 1 pi pi 12582912 Jul 9 13:38 ibdata1
-rwxrwxrwx 1 pi pi 50331648 Jul 9 13:38 ib_logfile0
-rwxrwxrwx 1 pi pi 50331648 Jul 1 06:34 ib_logfile1
-rwxrwxrwx 1 pi pi 0 Jul 1 06:34 multi-master.info
drwxrwxrwx 2 pi pi 4096 Jul 2 10:13 mysql
-rwxrwxrwx 1 pi pi 16 Jul 1 06:34 mysql_upgrade_info
drwxrwxrwx 2 pi pi 4096 Jul 2 10:13 performance_schema
drwxrwxrwx 2 pi pi 4096 Jul 2 12:49 test_db
THose question marks freak me out...tried deleting the ib_buffer_pool and just get this "Bad Message" thing over and over.
To get this setup working on my other pi's I had to change permissions with sudo chmod -R a+rwX directory/ and i did that for THIS pi also, thought maybe this was a permissions issue but I checked and the containing folders are all rwxrwxrwx also...
does anyone know what might be going on and how to resolve this so I can start a local mariadb server on this pi?
N.B. I do have a mariadb server successfully running on ANOTHER pi which THIS f-ed up pi is connected to via ethernet and I can connect to that OTHER pi's mariadb server with THIS f-ed up pi to manipulate data and so on, no problems. BUT I wanted to run a local mariadb server on THIS f-ed up pi ALSO (so it could manage a database which would be located on ITS respective harddrive)...is this kind of goal not possible and/or the cause of why my ib_buffer_pool has ??? ???? ???? and I'm getting exit-code when i try to start this local mariadb server? FYI
Much appreciated

Answer 1

okay just in case anyone else stumbles across this...
didn't fix it properly, BUT
it was the ib_buffer_pool file being corrupted that was the problem.
To make it work (but i don't think it's a good long term fix)
I just renamed the directory the ib_buffer_pool file was in to "directorynameCORRUPTED"
then created a new directory called "directoryname"
and copied all of the files from "directorynameCORRUPTED" other than ib_buffer_pool into this "directoryname" directory
And it worked. So it's a workaround...but still wanna know what to do about those ????? corrupted files why did it show up? troubling....