Latency with filesystems ending with _netdev attached to them
 

Users are complaining about super slow response times when they are copying data from Oracle server over to the storage device where these filesystems sit. Checked Storage and Network and both are clean, no issues in the logs.
I have filesystems listed below that show _netdev at the end of each line in /etc/fstab

/dev/helixoravg/oracle_data2_lv /oracle_data2 xfs _netdev 0 0
/dev/helixoravg/oracle_redo2_lv /oracle_redo2 xfs _netdev 0 0
/dev/orabackupvg/oracle_archive2_lv /oracle_archive2 xfs _netdev 0 0
/dev/orabackupvg/oracle_backup2_lv /oracle_backup2 xfs _netdev 0 0

I was told these should not be transferring over the network and using ISCI only. Anyone know how to fix this?

What distro and version are you using?
Are those logical volumes local on the server or remote? If local then _netdev would probably not be correct as a mount option.

It looks like you are missing the options field in those fstab entries. Since you posted without using the code tags I can see no space between xfs and _netdev. Is it "xfs_netdev" or "xfs _netdev"? Can't tell.
The lines would be much more readable if they looked like this
instead of this
/dev/mapper/fedora-root / ext4 defaults 1 1

That is the same line posted with code tags and without.

computersavvy, just hit the "Quote" button on the OP - you'll see the full layout as it was posted.

The mount manpage states that _netdev is only to wait for the network to come up before the mount is attempted. Can't see why it would affect operations after that.

syg00
Right and the above is ambiguous and implies data is being transferred across the network. I asked for additional information as well as suggesting the use of code tags, although I did misunderstand the man page.

If you mean iSCSI, then network transfers do occur (except if you import an iSCSI device on the same server where it is exported, which is not a usual configuration).

To fix performance problems like slow storage, I'd do something like this:

• Check if it has always slow. If not, check if any relevant configuration change took place when it started to be slow. Also check if the way the storage devices are used has changed (e.g., new or updated application).
• Run performance measurement tests myself. In the case of storage, vary parameters like I/O block sizes.
• If satisfied that the problem is caused by storage and not something else, start looking into storage-specific parameters.
• In the case of iSCSI, check system performance on client and server side. In particular IO performance on the server side. Also check network metrics such as high amount of retransmissions.
• Learn about parameters that might impact iSCSI performance and apply those.

Awesome information. Thank you all!!