Enabling Multipathing

[Elegant]

Hi guys,
So I'm now in a situation where multipathing would be of great use and would more than likely solve a few issues I'm having. First off, I DO have the equipment to support this, I have a backplane that has two LSI 9300-8i connected. My issue is that I have 6 drives but FreeNAS is seeing 12.

Now normally, I would not disrupt a working setup but it seems there are conflicts once every few weeks. The last incident was the last straw, I had to rebuild a drive because a SMART test failed and the raid degraded. To be clear it did not fail, it could not start a SMART test as it was already being performed by the other controller on the same drive and couldn't get the handle as per the log.

What is the safest way to create the multipathing after the pool exists? Export and reimport after using gmultipath? I tried a few things and had to use gpart recover to basically undo my crude attempt.

Any insight would be greatly appreciated. Thanks!

 

[dlavigne]

Which solution did you end up using?

 

[Elegant]

I'll answer this by starting with my setup, this is mainly for those who might try this later so they are aware of the performance:

I have 6 SATA disks, there should be NO speed increase as there is no secondary connection for SATA disks, only SAS disks. The reasoning for doing this in the first place is that I found there to be conflicts where the controllers would fight for control over a disk. You'd think that FreeNAS wouldn't use the other path at all but you'd be wrong. I have a pool that uses da6-11 (da0-5 are the other paths) and yet da4 (it varies) will have issues when it's not even part of the pool!

Solution: Since I am using a Z2 array I can manage to offline the drives one at a time and create a gmultipath and then reintroduce it into the raid. This DOES require resilvering which is NOT fun for my setup as I am still in the process of going through my drives. One must keep in mind that gmultipath will corrupt the GPT at the end of the drive, that is why a resilvering must be done as a gpart recover will not work.

I will (hopefully) provide an update once all my resilvering is complete to confirm if this solved my issue or if there is something wrong with my hardware either the HBAs or the backplane used in my server. The HBA card that has the issue along with the drive always varies it is never the same drive/path.