Thanks.

Cool post. I agree tape is a waste of…tape.

BTW, I hope you’re planning to buy a lot of tape drives: the LTO-4 quotes an MCBF of 100,000 load/thread/unload cycles. At 240 per drive per day (just 10 per hour!), you’ll replace that tape drive after a bit more than a year; at over $3000 per drive, that’s a big chunk of change. Not an issue for streaming backup, but definitely an issue for an archival storage system.

If you want to stream out backups (that you plan to never use), a system like Pergamum may not be the right choice. If you want an archival storage system (not a backup system), we believe that energy-efficient disk-based archives are the right way to go.

Steve, I see this as a replacement for the tape silo market, not tape itself. Do people routinely empty their tape silos and move all the tapes offsite? Also, if you look at the shock and vibe specs for tape cartridges they aren’t much better than spun-down disks. Him-m-m. . .

David, thanks for the additional analysis – good stuff! With some serious engineering: tight code; slow disk; HW parity assist and such the power and performance can be brought into line with tape – while retaining the massive advantage of rapid random access. Nobody wants to do legal discovery from a tape silo.

PTZ, Joe, I’ve written about Coraid in the past and would be happy to write about them again. I hear very little about them and so they don’t have much top of mind with me.

Robin

Coraid’s make for a great, inexpensive backup system. You can pop media out and put new media in (media == disk), and treat the media like tape. You can ship arrays out as whole backup units if you wish.

They are excellent backup devices and work quite well with our high performance storage units. They aren’t high speed in terms of storage, but 100 MB/s sustained (uncompressed) to disk, isn’t bad as a backup. Thats 1GB/10 seconds, 1 TB in 10,000 seconds. Since it is ATA over Ethernet, you can have multiple parallel streams. Coraid spec lets you get up to 40k drives per network segment, so, in theory, with a well design network and backup system (as well as a cluster of fast machines to save stuff off of), you may be able to achieve very high (sustainable) backup rates. 10 JackRabbits pumping data to 10 Coraid’s could conceivably back up 1 TB in 1000 seconds (under 1/3 of an hour). 100 such units of each may be able to achieve 1 TB in 100 seconds.

The pain will shift from depositing the data to managing the data streams and quality in this model, as well as media management, etc. This isn’t the tape rotation schedule issue, but rather how do you guarantee that you can always read data from a possibly unreliable spinning medium.

LTO-4 currently gets you 800 GB at 120 MB/s, uncompressed. If you need to string together several of the Pergamum systems to match that, then power may come out in a wash (Quantum’s LTO-4HH SAS drive uses 30.1 W max, 28.8 W typical, according to their spec sheet).

So, to get 120 MB/s, they need to use at least twelve units, which leads to 12 * 11.5 W = 138 W for 10 MB/s; 276 W for 24 units at 5 MB/s to reach 120 MB/s. Though one advantage of this system is that you can stream at any speed and you don’t have to worry about shoe-shining.

Sun’s T10000 gets you 500 GB at 180 MB/s, uncompressed, running at a max of 90 W according to the spec sheet. 36 * 11.5 W = 414 W to get 180 MB/s, if each Pergamum unit gives you 5 MB/s. The tape silos also take power, so for a fair comparison you should add that as well.

You’ll also have to rewrite software to to use Pergamum’s software interface (Section 3.3).

I still have to go through the paper more thoroughly, but this is an interesting research product that will hopefully give another option in protecting our data.

I think I’ve got an idea for my future startup

Both shifts will take years to materialize in a macro way, of course.