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From Alexis Rodríguez <arodrig...@inconcertcc.com>
Subject Re: How to make compaction run faster?
Date Wed, 17 Apr 2013 23:58:04 GMT
Jay,

I believe that compaction occurs on the data directories and not in the
commitlog.

http://wiki.apache.org/cassandra/MemtableSSTable




On Wed, Apr 17, 2013 at 7:58 PM, Jay Svc <jaytechgeek@gmail.com> wrote:

> Hi Alexis,
>
> Thank you for your response.
>
> My commit log is on SSD. which shows me 30 to 40 ms of disk latency.
>
> When I ran iostat; I see "await" 26ms to 30 ms for my commit log disk. My
> CPU is less than 18% used.
>
> How I reduce the disk latency for my commit log disk. They are SSDs.
>
> Thank you in advance,
> Jay
>
>
> On Wed, Apr 17, 2013 at 3:58 PM, Alexis Rodríguez <
> arodriguez@inconcertcc.com> wrote:
>
>> :D
>>
>> Jay, check if your disk(s) utilization allows you to change the
>> configuration the way Edward suggest. iostat -xkcd 1 will show you how much
>> of your disk(s) are in use.
>>
>>
>>
>>
>> On Wed, Apr 17, 2013 at 5:26 PM, Edward Capriolo <edlinuxguru@gmail.com>wrote:
>>
>>> three things:
>>> 1) compaction throughput is fairly low (yaml nodetool)
>>> 2) concurrent compactions is fairly low (yaml)
>>> 3) multithreaded compaction might be off in your version
>>>
>>> Try raising these things. Otherwise consider option 4.
>>>
>>> 4)$$$$$$$$$$$$$$$$$$$$$$$ RAID,RAM<CPU$$$$$$$$$$$$$$
>>>
>>>
>>> On Wed, Apr 17, 2013 at 4:01 PM, Jay Svc <jaytechgeek@gmail.com> wrote:
>>>
>>>> Hi Team,
>>>>
>>>>
>>>>
>>>> I have a high write traffic to my Cassandra cluster. I experience a
>>>> very high number of pending compactions. As I expect higher writes, The
>>>> pending compactions keep increasing. Even when I stop my writes it takes
>>>> several hours to finishing pending compactions.
>>>>
>>>>
>>>> My CF is configured with LCS, with sstable_size_mb=20M. My CPU is below
>>>> 20%, JVM memory usage is between 45%-55%. I am using Cassandra 1.1.9.
>>>>
>>>>
>>>> How can I increase the compaction rate so it will run bit faster to
>>>> match my write speed?
>>>>
>>>>
>>>> Your inputs are appreciated.
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Jay
>>>>
>>>>
>>>
>>
>

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