crash recovery

SUSE & openSUSE: "The Linux Kernel offers you something that allows you to recover your system from a crash or at the least lets you to perform a proper shutdown using the Magic SysRq Keys.

The magic SysRq key is a select key combination in the Linux kernel which allows the user to perform various low level commands regardless of the system's state"

The Linux Kernel offers you something that allows you to recover your system from a crash or at the least lets you to perform a proper shutdown using the Magic SysRq Keys.

The magic SysRq key is a select key combination in the Linux kernel which allows the user to perform various low level commands regardless of the system’s state using SysRq keys

The Dragonfly BSD 2.0 release is available.

The big change would appear to be the HAMMER filesystem, which supports snapshots, no-fsck crash recovery, mirroring, and more.

* Crash recovery on-mount, no fsck.* Fine-grained snapshots, snapshot management, snapshot-support for filesystem-wide data integrity checks.* Mirroring: Queueless incremental mirroring, master to multi-slave.* Undo and rollback and More...I can't wait for the multi-Master code to be released.

Keep up the good work!

Matthew Dillon announced the availability of DragonFly BSD 2.0: "2.0 is our eighth major DragonFly release.

DragonFly's policy is to only commit bug fixes to release branches." Changes in this release include: the HAMMER filesystem featuring crash recovery on-mount (without fsck) and queueless incremental mirroring, numerous kernel changes....

"Hurrah!

Matthew Dillon sent out a series of updates about his developing HAMMER filesystem, noting that he is currently focusing on the reblocking and pruning code, tracking down a number of bugs resulting in B-Tree corruption.

He also noted that previously HAMMER was comprised of three components: B-Tree nodes, records, and data.

"HAMMER is going to be a little unstable as I commit the crash recovery code," began DragonFly BSD creator Matthew Dillon, adding, "I'm about half way through it." He went on to list what's left for crash recovery to work with HAMMER, his new clustering filesystem, "I have to flush the undo buffers out before the meta-data buffers; then I have to flush the volume header so mount can see the updated undo info; then I have to flush out the meta-data buffers that the UNDO info refers to; and,

Matthew Dillon posted on update on his evolving HAMMER filesystem, noting that it "passes all standard filesystem stress tests and buildworld will run with a HAMMER /usr/obj".

He also noted, "pruning and reblocking code is in and partially tested, but now needs more stringent testing; full historical access appears to be working but needs testing." He added, "there are two big-ticket and several little-ticket items left.

"HAMMER won't be ready for sure (things take however long they take), but the hardest part is working and stable and I'm just down to garbage collection and crash recovery," noted Matthew Dillon, discussing the status of what is ultimately intended to be a highly available clustering filesystem.

The upcoming DragonFlyBSD release this month was originally intended to be 2.0 with a beta quality HAMMER, but the decision was recently made to call the release 1.12 while HAMMER continues to stabilize.

Matt continued, "HAMMER is really shaping up now.