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From Adar Dembo <a...@cloudera.com>
Subject Re: About data file size and on-disk size
Date Wed, 23 Nov 2016 01:35:25 GMT
Also, if you haven't explicitly disabled it, each .data file is going
to preallocate 32 MB of data when used. It's conceivable that there's
a pathological case wherein each of the 8133 data files is used, one
at a time, to store data blocks, which would cause each to allocate 32
MB of disk space (totaling about 254G).

Can you tell us a little bit more about your table, as well as any
deleted tables you once had? How many columns did they have? Also,
what version of Kudu are you using?

On Tue, Nov 22, 2016 at 11:39 AM, Adar Dembo <adar@cloudera.com> wrote:
> The files in /data/kudu/tserver/data are supposed to be sparse; that
> is, when Kudu decides to delete data, it'll punch a hole in one of
> those files, allowing the filesystem to reclaim the space in that
> hole. Yet, 'du' should reflect that because it measures real space
> usage. Can you try running du with --apparent-size and compare the
> results? If they're the same or similar, it suggests that the hole
> punching behavior isn't working properly. What distribution are you
> using? What filesystem is being used for /data/kudu/tserver/data?
>
> You should also check if maybe Kudu has failed to delete the data
> belonging to deleted tables. Has this tserver hosted any tablets
> belonging to tables that have since been deleted? Does the tserver log
> describe any errors when trying to delete the data belonging to those
> tablets?
>
> On Tue, Nov 22, 2016 at 7:19 AM, 阿香 <1654407779@qq.com> wrote:
>> Hi,
>>
>>
>> I have a table with 16 buckets over 3 physical machines. The tablet only has
>> one replica.
>>
>>
>> Tablets Web UI shows that each tablet has around ~4.5G on-disk size.
>>
>> In one machine, there are total  8 tablets, so the on-disk size is about
>> 4.5*8 = 36G.
>>
>> however, in the same machine, the disk actually used is about 211G.
>>
>>
>> # du -sh /data/kudu/tserver/data/
>>
>> 210G /data/kudu/tserver/data/
>>
>>
>> # find /data/kudu/tserver/data/ -name "*.data" | wc -l
>>
>> 8133
>>
>>
>>
>> What’s the difference between data file and on-disk size.
>>
>> Can files in  /data/kudu/tserver/data/ be compacted, purged, or some of them
>> be deleted?
>>
>>
>> Thanks very much.
>>
>>
>> BR
>>
>> Brooks
>>
>>
>>

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