Using xtrabackup for copying files can really saturate your disks, and that why we made special option --throttle=rate
to limit rate of IO per second. But it really works when you do local copy.
What about stream backup ? Even you copy just to remote box with
innobackupex --stream=tar | ssh remotebox "tar xfi -"
, read may be so intensive so your mysqld feels impact, slave getting behind, etc…
For this there is a nice small utility - pv .
With pv you run:
innobackupex --stream=tar | pv -q -L10m | ssh remotebox "tar xfi -"
and it will limit channel rate to 10 M per second.
Entry posted by Vadim | No comment
I should say I can see results of new engineering/refactoring/bug hunt efforts inside Sun/MySQL.
Over last couple of weeks I started getting a lot of messages from the bugs system about bugs I reported long ago which were deferred to be fixed later or were left in open state. Here is example of such a bug.
I really hope this effort will result in a lot of these old annoyances fixed, which really matches my vision for MySQL - we do not need more big features we need old ones to work well and be convenient.
Entry posted by peter | 2 comments
At the core of the new real-time web, which is really really old, are continuous queries. I like how this paper proposed to handle dynamic demand and dynamic resource availability by making the underlying system adaptable, which seems like a very cloudy kind of thing to do.
Abstract:
The long-running nature of continuous queries poses new scalability challenges for dataflow processing. CQ systems execute pipelined dataflows that may be shared across multiple
queries. The scalability of these dataflows is limited by their constituent, stateful operators – e.g. windowed joins or grouping operators. To scale such operators, a natural solution is to partition them across a shared-nothing platform. But in the CQ context, traditional, static techniques
for partitioned parallelism can exhibit detrimental imbalances as workload and runtime conditions evolve. Longrunning CQ dataflows must continue to function robustly in
the face of these imbalances. To address this challenge, we introduce a dataflow operator
called Flux that encapsulates adaptive state partitioning and dataflow routing. Flux is placed between producerconsumer stages in a dataflow pipeline to repartition stateful operators while the pipeline is still executing. We present the Flux architecture, along with repartitioning policies that can be used for CQ operators under shifting processing and memory loads. We show that the Flux mechanism and
these policies can provide several factors improvement in throughput and orders of magnitude improvement in average latency over the static case
A software-based distributed caching system such as memcached is an important piece of today's largest Internet sites that support millions of concurrent users and deliver user-friendly response times. The distributed nature of memcached design transforms 1000s of servers into one large caching pool with gigabytes of memory per node. This blog entry explores single-instance memcached scalability for a few usage patterns.
Table below shows out-of-the-box (no custom OS rewrites or networking tuning required) performance with 10G networking hardware and one single-socket UltraSPARC T2-based server with 8 cores and 8 threads per core (64 threads on a chip)...
Object Size / Ops/Sec / Bandwidth
100 bytes / 530,000 / 1.2 Gb/s
2048 bytes / 370,000 / 6.9 Gb/s
4096 bytes / 255,000 / 9.2 Gb/s
Check out the link for more details!
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