Anouncing new long term stable branch for CTDB: 1.13

[Amitay Isaacs]

Hi All,

On Thu, Mar 1, 2012 at 1:16 PM, ronnie sahlberg
<ronniesahlberg at gmail.com> wrote:
> List
>
> Please find new CTDB branch 1.13 available.
> This will be the new long term stable branch for CTDB and will start
> undergoing testing and stabilization over the next few time-units.
>
>
> The main new features in 1.13 are two significant performance
> improvements for certain workloads :
>
> * ReadOnly record support:  This is a new feature to introduce shared
> read-locks for the ctdb database.
> This greatly improves workloads where many processes are accessing the
> same record concurrently.
>
> An example workload that is improved by allowing shared-readlocks
> would be brlock.tdb for the case where many processes are
> reading/writing to the same file concurrently. This allows each node
> to have a local readonly copy of the database record associated to the
> file.
>
> SMBTORTURE testing for worst case workload (hundreds of SMBDs all
> reading from the same file) has shown performance improvements
> exceeding 10x
>
>
> * Fethc-Lock-Collapse: This is a new feature to rate-limit the number
> of concurrent requests for an exclusive-writelock for a record and
> improving scaling and performance.
> This greatly improves performance and reduces cpu utilization for
> common workloads where many clients are trying to write to the same
> record in the database.
> For example locking.tdb  with large number of clients opnening/closing
> the same file concurrently.
>
>
> In order to use/test  read-only records, you need a separate patch for
> samba which will be posted separately.
> The support is disabled by default but can be activated on a per
> database basis using :
>
> onnode all ctdb setdbreadonly brlock.tdb
>
> ctdb getdbmap | grep brlock.tdb
> dbid:0x4e66c2b2 name:brlock.tdb path:/var/ctdb/brlock.tdb.0 READONLY
> <-- this means the support is activated.
>
> doc/readonlyrecords.txt contains technical description on how they work.
>
> regards
> ronnie sahlberg

In addition, changes to SAMBA to enable read-only record support are
available here:

http://git.samba.org/?p=amitay/samba.git;a=shortlog;h=refs/heads/ctdb-readonly-wip

Amitay.