OS: SLES 12 for SAP SP 3 + fully updated/patched.

Once in a week, System(application and Database) becomes unresponsive due to I/O error.
While having I/O error, we can ping and access the system via SSH/PuTTY, though none of the standard linux command runs successfully due to I/O error:

:~ # top
:~ # /usr/bin/top: Input/output error
:~ # dmesg
:~ # /usr/bin/dmesg: Input/output error
:~ # tail -f /var/log/messages
:~ # /usr/bin/tail: Input/output error

The interesting part is that issue always gets fixed(for next 4-5 days) simply by hard rebooting the server(system didnt even reboots via command) and system keeps running without any issue till next I/O error(repeats every 5-6 days).

No single FS error is every reported(in the logs) on this system. We even run the file system checks too.

SUSE Support advised us
There is no errors or messages indicating issue on the file system level so far. I/O errors are not only related to File system.
By looking at the logs, it seems the memory cached keeps increasing and its not getting freed. I would recommend to tune up the memory as indicated in the TID below :
https://www.suse.com/support/kb/doc/?id=7021211

Please let me know once this is done and send me a new supportconfig.

We will then monitor the server behavior.
I am unable to understand how memory tuning would prevent the I/O error ? Interestingly this is the SAP HANA replication target, i.e this system is a Passive node, while we never ever face I/O errors on Master/Primary SAP Server.