philipp.reisner at linbit.com
Fri May 24 13:57:13 CEST 2019
As usual this release brings a number of bug fixes, that alone is
reason enough to recommend the upgrade to every user.
Exciting are the two new features:
Quorum tie breaker
So far enabling quorum only made sense if you have a three way
redundant data set. With the new quorum tie breaker feature
it works with 2 way redundnt data, but needs a 3rd, diskless node
in the DRBD resource.
optimized meta-data access if meta-data is on PMEM
PMEM (or NVDIMMs) is an exciting revolutionary change in computing.
It is a new storage tier that is connected as memory to the system.
One consequence of that is that software not gets the ability to
access/change/update data on the storage is smaller units than whole
sectors (512 bytes). We can not modify it in units of 64 bytes.
That gives us a DRBD developers new possibilities in optimizing
updates of our on-storage meta-data data structures.
We created a new PMEM optimized layout for the activity log, and
access the bitmap directly in place, as PMEM is memory mapped. As
a side consequence this reduces DRBD's memory consumption.
Depending on the workload you might get a 2x improvement in
write IOPs and a 4x improvement in throughput.
* Fix an IO deadlock under memory pressure
* Fix disconnect timing in case the network connection suddenly
drops all packets
* Fix some misbehavior that surfaced with Ahead/Behind
* Fix potential spinlock deadlock in IRQ
* Minor fixes: forget-peer, _rcu iterators
* Quickly stop resync during AHEAD/BEHIND by introducing new
packet for that purpose.
* The quorum feature can now use the connectivity to
the majority of Diskless nodes as tiebreaker
* Access meta-data using DAX if it is on persistent memory
(NVDIMM or PMEM); For write intense workloads this is a x2 to x4 speedup!
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