A Tour of btrfs – Avi Miller
- Now
- All data and metadata is copy-on-write
- CRC all metadata and data
- Writable snapshots
- multi-device support ( raid0 , raid1 , raid 10 )
- online resize and defrag, online device replace
- transparent compressions, efficient storage for small files
- Soon
- Fixes for perf and stability
- background scrubbing, LZO compression, batched discard, file defrag options, per-inode flags
- Larger block sizes for ( especially for metadata, to provide perf improvements in some cases)
- Scrubbing uses CRC to varify data on disk, fixes bad ones with good copy on another disk which has okay CRC
- “df ” gives completely wrong values on how full the disk is or it’s size
- discard/trim supported both real time and batched
- Drive Swapping – current raid rebuilds via balance code, can also restripe between RAID levels
- btrs send/receive in development
- Embedded – friendly to small machines, not as friendly to small disks (being worked on) Works well with low-end flash drives
- RAID 5/6 – MErge pending completion of fsck work. will also add triple mirroring
- beta read-only filesystem recovery tool – copies data out of corrupt FS
- tree root-history log lets us recovery from many hardware errors. “mount -recover”
- New fsck release on the way. May be announced very soon
- yum-plugin-fs-snapshot . yum plug to trigger a snapshot on package install/upgrades
The Web as an application development platform – Shane Stephens and Mike Lawther
- When and how to move from native to web/cloud apps
- Examples
- Text based like email (pine, mutt, outlook). 15 years ago web-based email started. access anywhere, no install required, easy to start using, use anywhere
- Desktop publishing. Hard to collaborate with other people using desktop based software by emailing docs around to other people. On the web it’s often native multi-user. Send Links rather than emailing whole doc.
- On web everybody always running latest version
- Github gives you one-stop shop for projects. wiki, forums etc. Native in app rather than bolt on to desktop version
- Graphics
- Flickr – has native sharing, backups etc
- Online editing of images etc now possible
- Games
- Farmville – no install, easy to share links
- Angry Birds – has web version, html5 , flash for sound, 60fps
- Not at stage where First person shooters going to happen yet. Users have high end hardware
- Overall Benefits – No install, universal access to data, always using latest version, collaboration and sharing built in. Simple text layout, Web as IDE, open and modular enviroment
- Drawbacks – Layout more involved than desktops apps, distributed code makes debugging hard, cross browser compatibility, security limits flexibility.
- Useful web technologies (see also HTML5Rocks website) :
- Display / Rendering
- HTML , SVG , Canvas – All fairly easy to combine
- WebGL , flexbox and grid <- future
- Communications
- Standard http requests, AJAX / XHR , Websockets / Browser Channel , libraries like Faye etc
- Storage
- Traditionally just cookies, Session Storage, Local Storage, indexDb, AppCache
- Environment Enhancements
- jQuery , CoffeeScript , NaCl