Share same extent to multiple clients

[SteffanCline]

I am using a Dell R710 with FreeNAS to provide service to 4x R610 via Fibre Channel. I followed this link to get it going.

https://forums.freenas.org/index.php?threads/fc-target-support-in-freenas-9-1-0.14139/page-2

On the R610s running CentOS 6 I am able to mount the extent I created in the link above but is it feasible to share the same extent with all 4x R610s simultaneously? When I try I get different sized extents rather than the same on all 4.

Suggestions?

 

[depasseg]

What filesystem is the extent formatted with (i.e. is is cluster aware)? Normally you can't hook multiple machines up to the same physical (in this case extent) disk and expect it to work. That link referenced VMware ESX which is cluster aware and knows how to handle multiple machines all being connected to the same extent.

 

[SteffanCline]

I did solely the portions that applied to FreeNAS from that article. I am using the fibre channel on CentOS Xen hosts (the R610s). The ext on the R710 was done with a GPT partition and ext4 for the FS. I'm not sure which partition scheme/FS is cluster aware. Is there one that is more suitable to make this work?

 

[depasseg]

I'm not familiar with how Xen handles its filesystem, sorry. I don't think that it will be ext4 though.

 

[SteffanCline]

In my case, xen is irrelevant. The purpose of the NAS at this point is to provide a volume/extent/etc to 4 CentOS servers over fibre channel so that they can all share the backup space. I am able to mount 1 extent on 1 server at a time. I'd rather not use 4 extents but it's looking as if I have to at this point.

 

[depasseg]

My point earlier is that you cannot access a single extent by more than one system unless each system is using a cluster aware filesystem. So find one for CentOS.

Does it have to be an extent? Can you use something like a file share (NFS)?

 

[SteffanCline]

Yes, it could be but I don't know how to make that accessible over fibre channel. Is there a tutorial for that?

 

[depasseg]

Dude, think of it this way. You are asking the equivalent of taking a single hard disk and hooking it up to multiple machines using SATA connections instead of sharing the drive space visa Ethernet.

Whatever reason is requiring you to use fibre channel should be answer to your clustering problem. Otherwise fibre channel is not required or multiple extents are the answer.

 

[SteffanCline]

Yeah, I thought about that but read that in certain contexts it was possible. The amount of documentation for FC is terrible. Not sure why. A 4GB FC card is $5 and the jumper is $5. So, for $20, you can connect 2 computers 4x faster than plain ethernet and FAR less than buying a 10GB ethernet card. I'll give a few other options a shot.

 

[depasseg]

A SAS3 cable is fast and cheap too, but that doesn't mean it will do what you need.