Ygtjki

we have linux DB server redhat 7.2

we notice about many message as below about all disks that are mounted

from /var/log/messages

what we are need to understand if this behavior is relevant to HW problem

Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4980*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4981*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4982*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4983*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4984*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4985*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4986*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4987*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4988*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4989*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4990*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4991*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4992*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4993*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4994*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4995*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4996*
Mar 29 13:28:22 server_DB kernel: Buffer I/O error on device sdb, logical block *N4997*

we also seen this messages

Mar 27 09:18:08 server_DB smartd[1734]: Monitoring 0 ATA and 26 SCSI devices
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:00/0000:00*CO*/0000:02*CO*': not supported by any plugin
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:00/0000:00*CO*/0000:02*CO*': not supported by any plugin
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:00/0000:00*CO*/0000:01*CO*': not supported by any plugin
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:00/0000:00*CO*/0000:01*CO*': not supported by any plugin
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:80/0000:80*CO*/0000:81*CO*': not supported by any plugin
Mar 27 09:18:08 server_DB ModemManager[1755]: <warn> Couldn't find support for device at '/sys/devices/pci0000:80/0000:80*CO*/0000:81*CO*': not supported by any plugin

I am also checked the disk

smartctl -a -d megaraid,0 /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.10.0-327.el7.x86_64] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor: SEAGATE
Product: ST600MM0238
Revision: BS04
User Capacity: 600,127,266,816 bytes [600 GB]
Logical block size: 512 bytes
Formatted with type 2 protection
Logical block provisioning type unreported, LBPME=0, LBPRZ=0
Rotation Rate: 10000 rpm
Form Factor: 2.5 inches
Logical Unit id: 0x5000c500a0f28343
Serial number: W0M0LYD2
Device type: disk
Transport protocol: SAS
Local Time is: Wed Mar 27 10:51:30 2019 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
Temperature Warning: Disabled or Not Supported

=== START OF READ SMART DATA SECTION ===
SMART Health Status: OK

Current Drive Temperature: 24 C
Drive Trip Temperature: 60 C

Manufactured in week 45 of year 2017
Specified cycle count over device lifetime: 10000
Accumulated start-stop cycles: 50
Specified load-unload count over device lifetime: 300000
Accumulated load-unload cycles: 177
Elements in grown defect list: 0

Vendor (Seagate) cache information
 Blocks sent to initiator = 412242328
 Blocks received from initiator = 3213595579
 Blocks read from cache and sent to initiator = 312462212
 Number of read and write commands whose size <= segment size = 31915885
 Number of read and write commands whose size > segment size = 0

Vendor (Seagate/Hitachi) factory information
 number of hours powered up = 3178.45
 number of minutes until next internal SMART test = 12

This I/O error message is written to warn about a hardware error with sdb. It could be with the disks or with the cable, for example.

I suppose it is less likely to be an error in the disks themselves, if you have a large number of disks all showing errors at the same time :-). It could be an error in the disk controller.

If you see "Buffer I/O error" but no specific messages about ATA or SCSI error codes, or about retry attempts in general, maybe that gives some hint. But I do not really know :-).

Of course, a software error could cause any messages whatsoever :-).

To give an example of a software error, although I know this is not the same error: I have seen a kernel bug where "Buffer I/O error" was shown, without any error messages about ATA or SCSI or retry attempts. Fedora bug 1553979.

The "Buffer" part just means that it happened during a request for file data which is cacheable in the page cache. For historical reasons, people sometimes call these requests "buffered IO".