And, one last thought, be careful about accidentally overriding walogs
for the metadata table. There isn't ever a reason to turn off walogs for
the metadata table (that I can think of).
I'm not sure if setting the table.walogs.enabled property in
accumulo-site.xml would override the value that is initially configured
on the metadata table or not. Hopefully not :)
On 5/17/14, 6:01 PM, Josh Elser wrote:
Absolutely, if you restrict a problem, you can work around it in other
ways. Not going to argue that.
Since this is a user list though, I got very worried seeing something
that roughly says "I'm benchmarking Accumulo with the WALs off". If
you're providing resiliency against data lost using other tactics,
that's fine, I just wanted to make sure that users who read this thread
later don't think that running tests against Accumulo with the WALs off
is "normal".
Looking forward to see the full picture of the benchmarks!
On 5/17/14, 5:27 PM, Jeremy Kepner wrote:
walog provides data loss protection in a specific set of circumstances.
Most of our deployments are under a different set of circumstances.
Accumulo is only one part of our systems and we have other
mechanisms for protecting against the loss of data.
We find the walog actually becomes a bottleneck in certain circumstances
and so turning it off increases the overall reliability of our system.
On Sat, May 17, 2014 at 04:27:29PM -0400, Josh Elser wrote:
You're likely to lose data in *any* deployment with the walogs turned
off.
And, to reiterate what Sean says, I wouldn't really consider any
benchmark with the walogs turned off valid except for "internal"
benchmarks (ones where we evaluate components only within Accumulo
for the sake of improving Accumulo itself and not comparing it to
other systems).
On 5/17/14, 3:30 PM, Sean Busbey wrote:
You can set both of those in the accumulo-site.xml.
However, it's going to be difficult to use benchmarks with walogs
disabled for valid comparisons to other systems. Also you are very
likely to lose data in any significantly sized deployment.
On Sat, May 17, 2014 at 1:35 PM, Kepner, Jeremy - 0553 - MITLL
<[email protected] <mailto:[email protected]>> wrote:
As part of our Accumulo benchmarking we have decided to set certain
values as defaults for all our databases:
tserver.compaction.minor.concurrent.max=5
table.walog.enabled=false
We were wondering which file(s) we would need to modify to apply
these defaults?
--
Sean
