We did this query, most our files are less than 100MB.

Our heap setting are like (they are calculatwed using scipr in
cassandra.env):
MAX_HEAP_SIZE="8GB"
HEAP_NEWSIZE="2GB"
which is maximum recommended by DataStax.

What values do you think we should try?





On Thu, Feb 26, 2015 at 10:06 AM, Roland Etzenhammer <
r.etzenham...@t-online.de> wrote:

> Hi Piotrek,
>
> your disks are mostly idle as far as I can see (the one with 17% busy
> isn't that high on load). One thing came up to my mind did you look on
> the sizes of your sstables? I did this with something like
>
> find /var/lib/cassandra/data -type f -size -1k -name "*Data.db" | wc
> find /var/lib/cassandra/data -type f -size -10k -name "*Data.db" | wc
> find /var/lib/cassandra/data -type f -size -100k -name "*Data.db" | wc
> ...
> find /var/lib/cassandra/data -type f -size -1000000k -name "*Data.db" | wc
>
> Your count is growing from opscenter - and if there are many really
> small tables I would guess you are running out of heap. If memory
> pressure is high it is likely that there will be much flushes of
> memtables to disk with many small files - had this once. You can
> increase heap in cassandra-env.sh, but be careful.
>
> Best regards,
> Roland
>
>

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