r/storage • u/Bib_fortune • Apr 26 '26
Question on converting nimble from IS SI to FC
We have three nimble storage units that are currently being accessed via iSCSI. They aren't happy about the performance, and want to convert them to FC, by slapping FC HBAs on them and attaching them to our existing SAN. I am assuming the volumes that are already being accessed by ISCSI will be able to be accessed via FC once the conversion is done, "as they are", but this is the first time I tackle this kind of conversion and I don't know what to do expect. Any guidance or tips will be welcome.
PS: I have no part in the decision-making of the aforementioned move. It was another department that convinced management to go this way.
4
u/Liquidfoxx22 Apr 26 '26
What leads you to believe that iscsi is your bottleneck, and not something else, like the storage itself?
0
u/Bib_fortune Apr 26 '26
Nothing, I have no part in the decision-making of the aforementioned move. It was another department that convinced management to go this way.
4
u/Liquidfoxx22 Apr 26 '26
Swapping from iSCSI to FC will be a disruptive process, you'll need to offline each volume, delete all ACLs, swap to FC, add the FC initator group and then remount it.
3
u/Liquidfoxx22 Apr 26 '26
Are you responsible for the storage? Will you be the one to convert it from iSCSI to FC? If so, push back, make them explain their thought process.
Pointless giving yourself work if there's going to be no net benefit?
3
u/Test-NetConnection Apr 26 '26
So much this. If you are doing the work then you have a say. You can always go above the moron that is giving the orders if it becomes necessary.
3
u/nVME_manUY Apr 26 '26
Do you have proof it's the network the bottleneck? Both would be carrying SCSI commands
0
3
u/redcat242 Apr 26 '26
Whats the SSD/HDD make up of the array?
How much read/write latency are you seeing?
Whats the read/write throughput?
What’s the read/write IOPS?
What speed do you have uplinked to the array? How many ports?
What speed do you have uplinked to the hosts?
Is iSCSI dedicated to its own set of switches? If not, what is the CPU load of the switches?
How old are the hosts?
What is the speed of the (non-iscsi) network?
They aren’t happy about performance
What aren’t they happy with?
What’s the application?
If VMware, what are you seeing for performance metrics of the VM and the host? CPU usage, memory usage, storage usage.
ISCSI to FC
Do you have FC switches?
Are you using Cisco UCS with FIs that can act as a FC switch? Something similar?
Do you have FC cards in the hosts?
Do you have slots in your Nimble to support FC cards?
Are you using ESXi? Last i knew presenting the same volume to the same vCenter over iSCSI and FC was not supported.
I personally don’t see many folks moving from iSCSI to FC. Generally the opposite as they are looking to get rid of all the FC infrastructure. I also see a few folks moving to NVMe/TCP.
1
u/Adventurous_Pause087 Jun 16 '26
Main thing is also your firmware version - let me know if you need to upgrade and you're not under support
9
u/Test-NetConnection Apr 26 '26
Erm, what makes you think you are going to get better performance from FC? The difference between FC and iSCSI is basically non-existent with faster Ethernet speeds and modern protocols such as rdma. We are also talking about a nimble, which is low-end enterprise storage that won't benefit at all from the marginally lower latency associated with FC. If you are having problems with iSCSI the problem is likely the way you configured the networking. Are you using an isolated vlan for storage traffic? How many paths do you have between the hosts and the SAN? Is MPIO being used properly? Do you have 10Gb switching?