The XtreemFS team released a new stable version of the cloud file system XtreemFS. XtreemFS 1.5 (Codename "Wonderful Waffles") comes with the following major changes:
- Improved Hadoop Support: Read and write buffers were added to improve the performance for small requests. The team also implemented support for multiple volumes e.g., to store input and output on volumes with different replication policies.
- SSDs support: So far, an OSD was optimized for rotating disks by using a single thread for disk accesses. Solid State Disks (SSDs) cope well with simultaneous requests and show a higher throughput with increased parallelism. To achieve more parallelism per OSD when using SSDs, multiple storage threads are supported now.
- Multi-Homing Support: XtreemFS can be made available for multiple networks and clients will pick the correct address automatically.
- Multiple OSDs per Machine: Machines with multiple disks have to run an OSD for each disk. The team simplified this process with the new xtreemfs-osd-farm init.d script.
- Bugfixes for Read/Write and Read-Only Replication: The team fixed a problem which prevented read/write replicated files to fail-over correctly. Another problem was that the on-demand read-only replication could hang and access was stalled.
- Replication Status Page: The DIR status page has got a visualization for the current replica status of open files. For example it shows which replica is the current primary or if a replica is unavailable.
The team prepared a tutorial which walks you through the setup of a read/write replicated XtreemFS volume on a single machine. The tutorial lets you stream a video from the volume and simulate the outage of a replica. You'll learn about the details of the XtreemFS replication protocol and why the video stalls for some seconds and then playback resumes.
AlmereGrid has put the tutorial to the next level: They created a setup of eight Raspberry Pi mini-computers running XtreemFS - packaged in a briefcase. Check the website CloudCase.eu for more details and the video which shows the briefcase and the demonstrated fail-over.
You can use XtreemFS directly in your application with our C++ and Java client libraries. This way you avoid any overhead due to Fuse and can access advanced XtreemFS features which are only available through the maintenance tool "xtfsutil" otherwise e.g., adding replicas.
From using XtreemFS it's only a small step to dive into the XtreemFS source code itself. The team collected several introductory documents for novices in a Google Drive folder "XtreemFS Public". For example, have a look how to setup the XtreemFS Server Java projects in Eclipse.
More information is available at http://xtreemfs.org/