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We are running multiple Dell PowerEdge's and want to connect them to a Dell TL1000 Tape Library.

For my understanding, what we need is HBA cards for each Server to get the SAS connection.

I ran into the problem, that the TL1000 provides only one SAS port. How can all Servers use the Tape Library? I thought of daisychaining the SAS cable thru each HBA and then to the TL, is this correct?

Moritz
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    I don't think this is really possible like this. Maybe the logical part on the SAS level could be handled with a SAS switch, but then you run into concurrency issues and other problem. The normal approach: Have only the backup server talking to the library and run backup clients on the servers that talk to the backup server. – Sven Sep 26 '18 at 14:49
  • Thanks, is it possible to run the backup server as a virtual machine? Or does it need to be dedicated? – Moritz Sep 26 '18 at 14:52
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    Depends on your virt software, but if you can pass through the SCSI device, it should work. – Sven Sep 26 '18 at 14:55

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I wouldn't do this at the SAS level, but at the software level. Most backup software supports storing data remotely; what you want is to do something like:

  • Have a backup server that's connected to your tape library
  • On that backup server, run some software that will schedule backups and write the data to tape
  • On each server that needs to be backed up, run an agent that will send the to-be-backed-up data to the backup server.

SAS multi-host communication like that doesn't work very well, and also isn't necessary.

As for an example of a particular piece of software, I have had good experiences running backups to a bacula server, as well as its fork, BareOS. Both support backing up Windows as well as Unix systems, although the backup server itself needs to run some form of Unix.

Wouter Verhelst
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  • I wouldn't exactly second "SAS is not meant for multi-host communication like that." because that's precisely what SCSI and SAS are actually about - multi-initiator setup *should* be no problem. In practice however, many devices, HBAs and especially drivers and software *can't* handle situations like that correctly and I wouldn't set it up either. – Zac67 Sep 28 '18 at 09:51
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    Fair enough, updated that comment. – Wouter Verhelst Sep 28 '18 at 14:26