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Storage expansion: iSCSI or Fibre Channel?

FC has lower protocol overhead and more stable latency, but needs FC switches and HBAs: expensive and specialist. iSCSI on 10G or 25G ethernet is usually the cheaper and more flexible choice for SMBs.

Try this first

  1. 1Inventory: how many hosts, which storage array, which workloads (VM storage, file storage, backup target).
  2. 2For 5 hosts or fewer with up to a few thousand IOPS: 10G iSCSI on dedicated VLAN or dedicated NICs is plenty. 25G or 100G is overkill for SMB workloads.
  3. 3Plan two independent paths (multi-pathing): two iSCSI VLANs on separate physical switches, MPIO on the hosts. Catches switch failure.
  4. 4Pick FC only if you have an existing FC fabric and know-how, or a specific application (extremely latency-sensitive OLTP). Otherwise iSCSI is the pragmatic call.
  5. 5For backup targets you may not even need iSCSI: an SMB3 share with RDMA on a Synology or Windows file server is fine and easier to manage.

When to bring us in

NVMe-over-fabrics (NVMe/TCP or NVMe/FC) is the future for high-end. Not yet relevant for SMB without matching arrays. Worth a look at the next refresh in 2027/2028.

See also

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