# External LTO drive



## giorgiov (Jan 4, 2016)

Hi all,
I’m trying to gather some data for an external (SCSI seems the best choice) LTO tape drive to be used with a workgroup server. The storage size requirements are about 5TB.

I have already investigated cloud-based solutions like Tarsnap and I’m a bit perplexed about the cost / benefit ratio with this amount of data, so I’d like to compare it with a more traditional solution, like tape.

I also took a look at vendors like Dell or Quantum, but it seems to me that their offering is targeted to a much higher market tier (something like a data center).

Any help and hint would be really appreciated.


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## leebrown66 (Jan 9, 2016)

Sorry for the length, this turned into a lengthier explanation than I imagined.  I've been looking at backup solutions for 32TB for a colleague...

When you say 5TB, is that the size for a full backup?  How frequently will you be doing full/increment/differential, and how much data to do anticipate for them.  How much time can you afford for the backup to run for?

Just for the full backup, for example (very quickly searched, based on first results, some are internal tape units):

An LTO-3 tape drive will cost about $200, a tape will hold 0.4T @ $20, so you'd need 13 tapes, totaling $260.  It runs at 80MB/s, which takes roughly 18hrs to run, including a little time to switch tapes.

An LTO-4 tape drive will cost about $600, a tape will hold 0.8T @ $16, so you'd need 7 tapes, totaling $112.  It runs at 120MB/s, which takes roughly 12hrs to run, including a little time to switch tapes.

An LTO-5 tape drive will cost about $1400, a tape will hold 1.5T @ $22, so you'd need 4 tapes, totaling $88.  It runs at 140MB/s, which takes roughly 10hrs to run, including a little time to switch tapes.

An LTO-6 tape drive will cost about $1800, a tape will hold 2.5T @ $30, so you'd need 2 tapes, totaling $60.  It runs at 160MB/s, which takes roughly 9hrs to run, including a little time to switch tapes.

An LTO-7 tape drive will cost about $3500, a tape will hold 6T @ $35, so you'd need 1 tape, totaling $35.  It runs at 140MB/s, which takes roughly 5hrs to run, including a little time to switch tapes.

Now account for your in-between full backups, that all depends on how much change you experience.  For example, 10% change per day would in the LTO3 case be about 1 tape per day, so assuming a full once per month, that's roughly 30 more tapes.

Now we get into retention:
If you want 3 months (again LTO3), we're at a total of (13+30)*3=129 tapes ($2580 in media cost).  Now that $3500 LTO7 tape drive doesn't seem so bad considering you need 9 tapes in total, for $315.  So you can see how it begins to even out.

Also in the LTO3 case, for example, an overnight full backup requires a human to change tapes every 80 minutes, so there's another cost to consider.  Alternatively you can get a robot tape changer, but that's going to jack you up into some serious money.

By comparison, a cloud backup, running at say 5MB/s (50mb/s), would take 12 days to run.

A RAID in another building over a gigabit connection is another option, but backup to disk is risky because a serious power event can take out everything.  Before I started working here, during a storm a tree fell, causing a 60kv line to fall onto a 6kv line (I think) and fried just about every electronic device on the property.  Blew up UPS's as well.

Other considerations are how frequently are you going to test the media, how long can you afford when a restore is needed and finally the cost of backup software.

So it's a question of time, budget, fluidity of change, retention period, how many tapes you want to juggle, cost of administering; versus the risk.


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## Terry_Kennedy (Jan 10, 2016)

giorgiov said:


> Hi all,
> I’m trying to gather some data for an external (SCSI seems the best choice) LTO tape drive to be used with a workgroup server. The storage size requirements are about 5TB.


You probably want to use SAS unless you have a computer with a legacy bus like classic (parallel) PCI. SAS HBAs like the Dell H200E are available in the $50 range on eBay. SAS cables are like SCSI cables - there are a large number of different, incompatible connectors. Buy your controller and drive first, then buy a cable that matches those connectors.


> I have already investigated cloud-based solutions like Tarsnap and I’m a bit perplexed about the cost / benefit ratio with this amount of data, so I’d like to compare it with a more traditional solution, like tape.


Unless you have a symmetric high-speed connection like 500/500 FiOS, you probably don't want to try to push 5TB upstream. If the data only changes slowly, some services will send you a drive to handle the initial "upload" and then you can back up the changed data over your ISP connection. Bear in mind that many ISPs cap the amount of data you can transfer in a billing period, so even if you have the speed you may not be able to use it.


> I also took a look at vendors like Dell or Quantum, but it seems to me that their offering is targeted to a much higher market tier (something like a data center).


Dell has "plain old tape drives" as well as autoloaders and libraries. But their prices are unreasonable. You can occasionally pick up new-in-the-box external drives on eBay for good prices ($500-ish for an LTO4HHv2). Beware of used eBay drives - many of them have high hours and have started to get flakey. Or they'll perform a "successful" backup even though there are lots of recovered errors and the drive's self-diagnostics fail.

I prefer IBM drives over other brands (note that many integrators such as Dell, HP, etc. use IBM drives as well as possibly other brands). Modern IBM LTO drives are dual-port SAS and have an Ethernet connector for diagnostic purposes.


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