Hammer and the future

Matthew Dillon’s been thinking about Hammer, and how to implement clustering well enough to work as a sort of RAID replacement.  He’s written up a document describing his plans.  Some highlights:

  • writable history snapshots
  • quotas and accounting
  • live rebuilds of data from mirrors
  • and the same history, mirroring, and snapshots as before.

It’s going to be a while before this “Hammer 2” becomes a finished product, though, so don’t count on it for the next release.

A start on TRIM support

Tim Bisson has inital TRIM support working for UFS.  His lengthy posting talks about how it’s done, and shows how much it speeds things up.  He’s looking for testers, so please try it if you have a SSD.  (The usual warnings apply about testing code that specifically deletes things.)

For those not familiar with TRIM in SSD context, here’s the least annoying page with an explanation that I could find in a few seconds of Googling.

GSoC: dsched BFQ, virtio, LVM mirror

Yay acronyms! Brills Peng was accepted for the Summer of Code project “Improve dsched interfaces and implement BFQ disk scheduling policy” – and now there’s a nice writeup describing what’s planned. Also, Stéphanie Ouillon did the same thing for the virtio drivers project.  Adam Hoka also joined in with a summary for his LVM mirror project.  Please keep this up, students.

dragonflybsd.it available

If you are a European resident, Federico Biancuzzi has the DRAGONFLYBSD.IT domain name available to donate. He doesn’t want to let it go and have it taken by a domain squatter. Talk to him at sale@securitydaemon.com if you want to hold on to it for some unspecified time.

Summer of Code DragonFly projects announced

Google’s announced the accepted projects for 2011.  DragonFly has 6 slots!

We had a large number of interesting project proposals; far more than than the slots available.  If you’re one of the students who did not get in, please consider working on your project as time allows.  I know it won’t be lucrative, but I’d still like to see them happen.

Here’s the list of accepted projects:

  1. Implementing a mirror target for device mapper: Adam Hoka, mentored by Joe Talbott
  2. Improve dsched interfaces and implement BFQ disk scheduling policy: Brills Peng, mentored by Alex Hornung
  3. Make vkernels checkpointable: Irina Presa, mentored by Venkatesh Srinivas
  4. Port PUFFS from NetBSD/FreeBSD: nickprok, mentored by Nathaniel Filardo
  5. Bring kernel event notification in DragonFly BSD to its logical conclusion: Samuel J. Greear, mentored by Sascha Wildner
  6. Porting Virtio Drivers from NetBSD to DragonFly BSD to speed up DragonFly BSD as a KVM guest: Stéphanie Ouillon, mentored by Pratyush Kshirsagar

 

Sysbench and DragonFly releases

I did some comparative benchmarking between the 2.6, 2.8, and upcoming 2.10 release for DragonFly.   As several people have guessed, performance has improved significantly, and the difference would probably be even more pronounced if I was using more modern hardware,  e.g. swapcache or a system with AHCI.  I have a mailing list post with details, and here’s the graph that sums it up:

Shorter bars are better(Sorry, no Lazy Reading this week.  Life didn’t co-operate.  At least there’s a pretty graph!)

 

Zombie shirts

Not shirts with zombies on them, but DragonFly shirts that don’t have a seller.  I had a random Google search turn up a store selling DragonFly T-shirts, among other things.  It was essentially a spam store.  The seller wasn’t producing anything but instead reselling other people’s material for a commission, similar to the splogs out there that recopy material from other blogs or Wikipedia and slap ads on it.  (I’ve seen Digest material pop up that way.)

Following the link back shows that the shirt is sold through a Cafepress store called ossgear.  It looks like the original store owner asked permission to use the logo back in 2006.  ossgear.org is no longer a functioning domain, and I can’t find any other reference to this seller; they appear to have stopped doing business 5 years ago.

The moral of this story: Sites like Cafepress will try to profit from your work long after you’ve stopped using them.  The frustrating part is that the logo isn’t even right!

RAM vs. deduplication

Tomas Bodzar asked about RAM usage with Hammer and deduplication, pointing at this example that shows ZFS requiring…  I’m not sure.  Lots?  Anyway, Matthew Dillon noted that offline deduplication in Hammer would use available RAM/swap for CRCs on all files, but only a limited subset for ‘live’ dedup.  For a real-world example, Venkatesh Srinivas described deduplicating about 600G down to 400G, with a machine having only 256M of RAM. Yes, only 256M.