On Mon, 18 Jun 2012, Ken Teh wrote:

> Hi all,
>
> I need some help and advice with LTO tape drives.  I haven't kept up with 
> tape technology for several years now and from a quick google, it appears 
> that the only games in town are LTO and DDS.  We do have a single DDS 
> deployment and we are looking at replacing it with LTO because of capacity 
> limitations.
>
> Some questions:
>
> (1) It appears that LTO-5 is the current technology. But most single drives 
> use SAS as an interface.  Again, I am not familiar with SAS.  All I know is 
> what the acronym stands for.  Is it a simple matter of buying a SAS card? 
> Will it run out of the box on a SL6.x box?  Any issues with drivers?
>
> (2) I see that LTO-4 is still available.  And a quick google suggests that 
> Ultra160 or 320 LVD SCSI is the more common interface for these drives.  I 
> have several of the Adaptec 29xxx cards, made available when we transitioned 
> to SATA.  Is this viable or would you recommend against using LTO-4?  It 
> appears to be about 5 years old.  I think it would be preferable to use 
> technology that has at least some life to it but I am not inclined to work 
> very hard to make LTO-5 work if it is not well supported on Linux.
>
> We are not looking to do anything fancy.  A single internal drive and a box 
> of tapes.  Backups the old fashioned way.
>
> Specific recommendations welcomed.  As in, buy this card, buy this drive!

We are using a Dell-provided LTO-5 library which appears to be a re-badged 
IBM model...  ie in /proc/scsi/scsi both the changer and the tape drive 
show up as IBM models:

...
Host: scsi1 Channel: 00 Id: 00 Lun: 00
   Vendor: IBM      Model: ULT3580-HH5      Rev: A422
   Type:   Sequential-Access                ANSI SCSI revision: 06
Host: scsi1 Channel: 00 Id: 00 Lun: 01
   Vendor: IBM      Model: 3573-TL          Rev: 9.50
   Type:   Medium Changer                   ANSI SCSI revision: 05
...

We talk to it using a Dell-provided SAS card which is a re-badged LSI e.g. 
from lspci:

...
04:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008
  PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 02)
...

This is automatically detected and seems to work fine with sl5.7, I've not 
tested it with anything much older. (It seems to use the mpt2sas driver 
from what I can tell).

So far we havn't noticed any problems though we are just going through 
setting up and testing bacula with it (to replace an older setup with an 
LTO-3 library on an sl4 box) so it hasn't had significant use yet.

  -- Jon