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We want to change our tape backup system and acquire a LTO8 tape drive.

Something that I cannot find the answer easily is what are the pro&con of the connectivty by Fiber channel or SAS.

For the moment I have find that :

  • SAS 6Gb max // Direct connection less latency // Need SAS card on the server (or hypervisor)
  • Fiber 10Gb max // can be shared by several Servers // A virtual server can be used

Our network for internal server is 10Gb so It's tempting to take the fiber option.

Do I forget something ?

Edit : Our Configuration is a 10 Gb Network dedicated (No VLAN tags) Admin Lan mixed in Rj45 and FC (which means only NAS servers // Replication server // Backup server // switches).

So the tape drive will be connected directly to a Switch//Server not a SAN.

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  • One more plus point for fiber: Depending on your backup software and setup, you can have backups over fiber - SAN network. Using directly connected SAS tape, you can only use ethernet network for backup. Your ethernet network may be 10Gb, but still it's nice to have the alternative option to use the SAN network.
    – Krackout
    Oct 12, 2020 at 9:02
  • I'm not sure to understand well. You mean that the SAN network system can access also the tape ?
    – Vindic
    Oct 12, 2020 at 14:18
  • Please edit your question to add details about your storage networks. Do you already use FC? Will FC will be Ethernet encapsulated? Is it shared with non-storage IP networks, or with non-backup networks?
    – John Mahowald
    Oct 12, 2020 at 15:16

3 Answers 3

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You order whatever fits your current equipment/strategy. Performance-wise there's no difference.

SAS is generally cheaper for direct-attached but Fibre Channel offers the opportunity for FC SAN integration.

Our network for internal server is 10Gb

Your Ethernet network doesn't matter - Fibre Channel is not compatible with that. If you're not already into FC, go with SAS.

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Fibre means Fibre channel and they come in 8gig speeds. 10Gig refers to Ethernet. SAS drives are actually less expensive. If you buy an FC tape Library - then you also need to buy a FC switch to connect into a SAN. with multiple servers - sharing in a SAN is awesome as it pulls all the data traffic away from your LAN. If it for a standalone server - then SAS is much cheaper way to go.

For an alternative SAN solution you can actually use a Bridge from a company called ATTO.com - they have both a FC-to-SAS and an Ethernet-to-SAS bridge. So you don't have to buy a switch, save big on cabling and much easier management. Check this out: https://www.atto.com/pdfs/Comparison-of-Native-Fibre-Channel-Tape-and-SAS-Tape-Connected-to-a-Fibre-Channel-to-SAS-Bridge.pdf Good luck

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I'm posting my comment as an answer, to add url links. I'll also clarify.

One more plus point for fiber: Depending on your backup software and setup, you can have backups over fiber, FC/SAN network. Using directly connected SAS tape, you can only use ethernet network for backup. Your ethernet network may be 10Gb, but still it's nice to have the alternative option to use the SAN network.

If a backup server, tape and the rest of the machines to be taken backup are connected to FC storage network, it's possible for the data to be transfered directly from machine to tape. At the start of the backup job, the backup agent on the machine will communicate with the backup server over ethernet network, for info like which data will be taken backup and afterwards the data can be transfered through FC storage network, direct connection between machine and tape. You can also balance your jobs, some backups over ethernet, others over fiber.

For backup over fibre to work, you need to setup backup server and clients accordingly. I do not endorse any products, I have just set up and used Veritas Netbackup and IBM's TSM (Spectrum nowadays) with this feature enabled and can confirm it can be done on these products. Others can also do it I suppose, make your research.

NetBackup SANClient & FibreTransport
IBM TSM/Spectrum LAN-free

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