[Beowulf] Re: OT: LTO Ultrium (3) throughput?

[Steve Cousins]

>
> From: "Jon Aquilina" 
>
> this is slightly off topic but im just wondering why spend thousands of
> dollars when u can just setup another server and backup everything to a
> raided hard drive array?

Another RAID system helps but only if it is located somewhere else. The 
main reason we backup is for disaster recovery. One nice thing about tape 
is that you can take the tapes to another location easily or put them in a 
fire safe.

Another reason is that RAID systems don't scale up as easily as a tape 
system. Our library has two 15 tape magazines that can be removed and 
replaced. It costs about $750 to buy 15 new tapes plus a magazine. That's 
not too bad for 6 TB of storage (uncompressed, with HW compression we get 
about 9 TB). Plus it takes practically no time to start using it.

The library wasn't really that expensive when we bought it either. 
Somewhere around $7500. At the time we bought that we were using 400 GB 
drives in our RAID systems at $300 each. To build a server with 5 TiB 
(usable) of RAID storage at the time was about $7000. The tapes were more 
expensive then (about $100 each) but for about $10,500 we got 12 TB of 
tape storage (library plus 30 tapes). To get roughly the same of disk 
storage would have been about $14K. So right off the bat tape was cheaper. 
Plus it is so much easier to manage. I like the idea of snapshots and 
using rsync plus links is a crafty idea but I sleep better knowing that I 
have a "real" (one that I can carry around) backup of our data in our 
safe.

Steve