if you don't want to lose data, don't wipe your commit logs. that
part seems pretty obvious to me. :)
cassandra aggressively logs its state when it is running out of memory
so you can troubleshoot. look for the GCInspector lines in the log.
but in this case it sounds pretty simple; you will be
There seems to have been a fair amount of discussion on memory related
issues so I apologize if this exact situation has come up before.
I am currently in the process of load testing an metrics platform I have
written which uses Cassandra and I have run into some very troubling issues.
The app
Also, in general, you probably want to set Xms = Xmx (regardless of the
value you eventually decide on for that).
If you set them equal, the JVM will just go ahead and allocate that amount
on startup. If they're different, then when you grow above Xms it has to
allocate more and move a bunch of s
Good point..
Thanks to both of you for the replies.
Kannan
From: Matthew Dennis
To: user@cassandra.apache.org
Sent: Thu, October 7, 2010 4:59:28 PM
Subject: Re: Heap Settings suggestions
Keep in mind that .7 and on will have per-CF settings for most things s
Allan,
I'm confused on why removetoken doesn't do anything and would be interested
in finding out why, but to answer your question:
You can shutdown down your last node, nuke the system directory (make a
backup just in case), restart the node, load the schema (export it first if
need be) and be o
Yes.
You probably shouldn't ever be using CL.ANY (though I'm certain there are
others that disagree with me; I wish them the best of luck with that).
CL.ONE + periodic sync can potentially lose recently written data, but if
you care about that then you better care enough about your data to use
so
Allan, I'm a bit confused about what you are trying to do here. You have 2 nodes with RF = ? , you lost one node completely and now you want to...Just get a cluster running again, don't worry about the data.ORRestore the data from the dead node. ORCreate a cluster with the data from the remaining n
Are there any data loss concerns if you have the commit log sync set to
periodic and are writing with CL One or Any?
From: Matthew Dennis [mailto:mden...@riptano.com]
Sent: Wednesday, October 06, 2010 8:53 PM
To: user@cassandra.apache.org
Subject: Re: Newbie Question about restarting Cassandra
+1 on disabling swap
On Oct 7, 2010 3:27 PM, "Peter Schuller"
wrote:
>> The nodes are still swapping, even though the swappiness is set to zero
>> right now. After swapping comes the OOM.
>
> In addition to what's already been said, consider just flat out
> disabling swap completely, unless you ha
Keep in mind that .7 and on will have per-CF settings for most things so
there will be even more control over the the tuning...
On Oct 7, 2010 3:10 PM, "Peter Schuller"
wrote:
>> What if there is more than one keyspace in the system ? Assuming each
>> keyspace has the same number of column familie
I recently posted a blog article about Cassandra and EC2 performance testing
for small vs large, EBS vs ephemeral storage, compared to real HW with and
without an SSD. Hope people find it interesting.
http://www.coreyhulen.org/?p=326
Highlights:
- The variance in test results from run to run
I was able to figure out to use the sstable2json tool to get the values out of
the system keyspace.
Unfortunately, the node that went down took all of it's data with it and I only
have access to the system keyspace of the remaining live node. There were only
two nodes and the one left should ha
Hey all,
I had a node go down that I'm not able to get a token for from nodetool ring.
The wiki says:
"You can obtain the dead node's token by running nodetool ring on any live
node, unless there was some kind of outage, and the others came up but not the
down one -- in that case, you can ret
> There's some words on the 'Net that - the recent pages on
> Riptano's site in fact - that strongly encourage scaling left
> and right, rather than beefing up the boxes - and certainly
> we're seeing far less bother from GC using a much smaller
> heap - previously we'd been going up to 16GB,
> The nodes are still swapping, even though the swappiness is set to zero
> right now. After swapping comes the OOM.
In addition to what's already been said, consider just flat out
disabling swap completely, unless you have other things on the machine
that cause swap to be significantly useful (i.
> What if there is more than one keyspace in the system ? Assuming each
> keyspace has the same number of column families, Can I linearly scale the
> above recommendation to the number of keyspaces in the system .ie, if the
> "X" is the heap size for a single keyspace and there are "Y" keyspaces, I
>From the Cassandra documentation @ riptano I see the following recommendation
for Heap size setting
MemtableThroughputInMB * 3 * (number of ColumnFamilies) + 1G + (size of
internal
caches)
What if there is more than one keyspace in the system ? Assuming each keyspace
has the same number of c
Also, as a note related to EC2, choose whether you want to be in multiple
availability zones. The highest performance possible is to be in a single
AZ, as all those machines will have *very* high speed interconnects. But,
individual AZs also can suffer outages. You can distribute your instances
if you are updating columns quite rapidly, you will scatter the columns
over many sstables as you update them over time. this means that a read
of a specific column will require looking at more sstables to find the
data. performing a compaction (using nodetool) will merge the sstables
into on
> However Ben Black suggests here that the cleanup will actually only
> impact data deleted through the API:
>
> http://comments.gmane.org/gmane.comp.db.cassandra.user/4437
>
> In this case, I guess that we need not worry too much about the
> setting since we are actually updating, never deleting.
On Thu, Oct 7, 2010 at 10:13 AM, Christian Decker
wrote:
> So basically my indices should work? Is there a simple way to check that, so
> that we can exclude that?
>
> Are LTE working (or on the roadmap for the 0.7.0 release)?
No, LT[E] is not on the roadmap for primary index clauses (GT[E] is,
f
Actually, you're trying to add an index to an already existing column family
here, right?
That's not yet supported, but should be soon.
- Tyler
On Thu, Oct 7, 2010 at 10:13 AM, Christian Decker <
decker.christ...@gmail.com> wrote:
> So basically my indices should work? Is there a simple way to
So basically my indices should work? Is there a simple way to check that, so
that we can exclude that?
Are LTE working (or on the roadmap for the 0.7.0 release)? Or does the EQ
operator have to math anything or can I just add an EQ to a not existing
value to get LTE working too?
Regards,
Chris
O
What I've tested you must include at least one expression with EQ operator
On Thu, Oct 7, 2010 at 3:45 PM, Matthew Dennis wrote:
> If I remember correctly the only operator supported for secondary indexes
> right now is EQ, not LTE (or the others).
>
>
> On Thu, Oct 7, 2010 at 6:13 AM, Christian
This is not in beta2 but will be in 0.7.0
(https://issues.apache.org/jira/browse/CASSANDRA-1532)
On Thu, Oct 7, 2010 at 7:30 AM, wrote:
> Hello,
>
> I am trying to work out the new secondary index code on my own, as there
> is no documentation. I've seen the 'Cassandra explained' presentation an
If I remember correctly the only operator supported for secondary indexes
right now is EQ, not LTE (or the others).
On Thu, Oct 7, 2010 at 6:13 AM, Christian Decker wrote:
> I'm currently trying to get started on secondary indices in Cassandra
> 0.7.0svn, but without any luck so far. I have the
I'm currently trying to get started on secondary indices in Cassandra
0.7.0svn, but without any luck so far. I have the following code that should
create an index on ColA:
KsDef ksDef = client.describe_keyspace("MyKeyspace");
> List cfs = ksDef.cf_defs;
> String columnFamil
Hi all
We're rolling out a Cassandra cluster on EC2 and I've got a couple if
questions about settings. I'm interested to hear what other people
have experienced with different values and generally seek advice.
*gcgraceseconds*
Currently we configure one setting for all CFs. We experimented with
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