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From Jay Svc <jaytechg...@gmail.com>
Subject Re: How to make compaction run faster?
Date Wed, 17 Apr 2013 22:58:15 GMT
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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