Hi G110YD - Thanks for posting this question to the forum.
I recommend not using a numeric value for the "no_path_retry" variable within /etc/multipath.conf as once that numeric value is reached, if no healthy LUNs were discovered during that defined time multipath will disable the I/O queue altogether.
I do recommend, however, changing the variable value from "12" (or even "60") to "queue" which will then allow multipathd to continue queing I/O until a healthy LUN is discovered (time of fail-over between controllers) and I/O is allowed to flow once again.
A recent publication concerning the Best Practices around Dell PS Series storage and SLES 12 SP1 host configuration covers some of the /etc/multipath.conf values in more detail. This guide can be found here
It may be of some benefit to you, if not locked into native iSCSI on RHEL, to look into the Dell EqualLogic HIT/Kit (Host Installation kit) for Linux to handle the MPIO of the host for you.
We, the Storage Applications Engineering team, produce many valuable documentation resources around Linux configuration of both Dell PS (EqualLogic) and Dell SC (Compellent) Storage, which can be found at: www.dell.com/StorageResources
SAE_StevenL
1 Message
1
October 5th, 2016 08:00
Hi G110YD - Thanks for posting this question to the forum.
I recommend not using a numeric value for the "no_path_retry" variable within /etc/multipath.conf as once that numeric value is reached, if no healthy LUNs were discovered during that defined time multipath will disable the I/O queue altogether.
I do recommend, however, changing the variable value from "12" (or even "60") to "queue" which will then allow multipathd to continue queing I/O until a healthy LUN is discovered (time of fail-over between controllers) and I/O is allowed to flow once again.
A recent publication concerning the Best Practices around Dell PS Series storage and SLES 12 SP1 host configuration covers some of the /etc/multipath.conf values in more detail. This guide can be found here
It may be of some benefit to you, if not locked into native iSCSI on RHEL, to look into the Dell EqualLogic HIT/Kit (Host Installation kit) for Linux to handle the MPIO of the host for you.
We, the Storage Applications Engineering team, produce many valuable documentation resources around Linux configuration of both Dell PS (EqualLogic) and Dell SC (Compellent) Storage, which can be found at: www.dell.com/StorageResources