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From Stephen Meyles <smey...@gmail.com>
Subject Re: Accumulo on Google Cloud Storage
Date Fri, 22 Jun 2018 17:50:23 GMT
Knowing that HBase has been run successfully on ADLS, went looking there
(as they have the same WAL write pattern). This is informative:


https://www.cloudera.com/documentation/enterprise/5-12-x/topics/admin_using_adls_storage_with_hbase.html

which suggests a need to split the WALs off on HDFS proper versus ADLS (or
presumably GCS) barring changes in the underlying semantics of each. AFAICT
you can't currently configure Accumulo to send WAL logs to a separate
cluster - is this correct?

S.


On Fri, Jun 22, 2018 at 9:07 AM, Stephen Meyles <smeyles@gmail.com> wrote:

> > Did you try to adjust any Accumulo properties to do bigger writes less
> frequently or something like that?
>
> We're using BatchWriters and sending reasonable larges batches of
> Mutations. Given the stack traces in both our cases are related to WAL
> writes it seems like batch size would be the only tweak available here
> (though, without reading the code carefully it's not even clear to me that
> is impactful) but if there others have suggestions I'd be happy to try.
>
> Given we have this working well and stable in other clusters atop
> traditional HDFS I'm currently pursuing this further with the MS to
> understand the variance to ADLS. Depending what emerges from that I may
> circle back with more details and a bug report and start digging in more
> deeply to the relevant code in Accumulo.
>
> S.
>
>
> On Fri, Jun 22, 2018 at 6:09 AM, Maxim Kolchin <kolchinmax@gmail.com>
> wrote:
>
>> > If somebody is interested in using Accumulo on GCS, I'd like to
>> encourage them to submit any bugs they encounter, and any patches (if they
>> are able) which resolve those bugs.
>>
>> I'd like to contribute a fix, but I don't know where to start. We tried
>> to get any help from the Google Support about [1] over email, but they just
>> say that the GCS doesn't support such write pattern. In the end, we can
>> only guess how to adjust the Accumulo behaviour to minimise broken
>> connections to the GCS.
>>
>> BTW although we observe this exception, the tablet server doesn't fail,
>> so it means that after some retries it is able to write WALs to GCS.
>>
>> @Stephen,
>>
>> > as discussions with MS engineers have suggested, similar to the GCS
>> thread, that small writes at high volume are, at best, suboptimal for ADLS.
>>
>> Did you try to adjust any Accumulo properties to do bigger writes less
>> frequently or something like that?
>>
>> [1]: https://github.com/GoogleCloudPlatform/bigdata-interop/issues/103
>>
>> Maxim
>>
>> On Thu, Jun 21, 2018 at 7:17 AM Stephen Meyles <smeyles@gmail.com> wrote:
>>
>>> I think we're seeing something similar but in our case we're trying to
>>> run Accumulo atop ADLS. When we generate sufficient write load we start to
>>> see stack traces like the following:
>>>
>>> [log.DfsLogger] ERROR: Failed to write log entries
>>> java.io.IOException: attempting to write to a closed stream;
>>> at com.microsoft.azure.datalake.store.ADLFileOutputStream.write
>>> (ADLFileOutputStream.java:88)
>>> at com.microsoft.azure.datalake.store.ADLFileOutputStream.write
>>> (ADLFileOutputStream.java:77)
>>> at org.apache.hadoop.fs.adl.AdlFsOutputStream.write(AdlFsOutput
>>> Stream.java:57)
>>> at org.apache.hadoop.fs.FSDataOutputStream$PositionCache.write(
>>> FSDataOutputStream.java:48)
>>> at java.io.DataOutputStream.write(DataOutputStream.java:88)
>>> at java.io.DataOutputStream.writeByte(DataOutputStream.java:153)
>>> at org.apache.accumulo.tserver.logger.LogFileKey.write(LogFileK
>>> ey.java:87)
>>> at org.apache.accumulo.tserver.log.DfsLogger.write(DfsLogger.java:537)
>>>
>>> We have developed a rudimentary LogCloser implementation that allows us
>>> to recover from this but overall performance is significantly impacted by
>>> this.
>>>
>>> > As for the WAL closing issue on GCS, I recall a previous thread about
>>> that
>>>
>>> I searched more for this but wasn't able to find anything, nor similar
>>> re: ADL. I am also curious about the earlier question:
>>>
>>> >> Does Accumulo have a specific write pattern [to WALs], so that file
>>> system may not support it?
>>>
>>> as discussions with MS engineers have suggested, similar to the GCS
>>> thread, that small writes at high volume are, at best, suboptimal for ADLS.
>>>
>>> Regards
>>>
>>> Stephen
>>>
>>>
>>> On Wed, Jun 20, 2018 at 11:20 AM, Christopher <ctubbsii@apache.org>
>>> wrote:
>>>
>>>> For what it's worth, this is an Apache project, not a Sqrrl project.
>>>> Amazon is free to contribute to Accumulo to improve its support of their
>>>> platform, just as anybody is free to do. Amazon may start contributing more
>>>> as a result of their acquisition... or they may not. There is no reason to
>>>> expect that their acquisition will have any impact whatsoever on the
>>>> platforms Accumulo supports, because Accumulo is not, and has not ever
>>>> been, a Sqrrl project (although some Sqrrl employees have contributed), and
>>>> thus will not become an Amazon project. It has been, and will remain, a
>>>> vendor-neutral Apache project. Regardless, we welcome contributions from
>>>> anybody which would improve Accumulo's support of any additional platform
>>>> alternatives to HDFS, whether it be GCS, S3, or something else.
>>>>
>>>> As for the WAL closing issue on GCS, I recall a previous thread about
>>>> that... I think a simple patch might be possible to solve that issue, but
>>>> to date, nobody has contributed a fix. If somebody is interested in using
>>>> Accumulo on GCS, I'd like to encourage them to submit any bugs they
>>>> encounter, and any patches (if they are able) which resolve those bugs. If
>>>> they need help submitting a fix, please ask on the dev@ list.
>>>>
>>>>
>>>>
>>>> On Wed, Jun 20, 2018 at 8:21 AM Geoffry Roberts <threadedblue@gmail.com>
>>>> wrote:
>>>>
>>>>> Maxim,
>>>>>
>>>>> Interesting that you were able to run A on GCS.  I never thought of
>>>>> that--good to know.
>>>>>
>>>>> Since I am now an AWS guy (at least or the time being), in light of
>>>>> the fact that Amazon purchased Sqrrl,  I am interested to see what develops.
>>>>>
>>>>>
>>>>> On Wed, Jun 20, 2018 at 5:15 AM, Maxim Kolchin <kolchinmax@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi Geoffry,
>>>>>>
>>>>>> Thank you for the feedback!
>>>>>>
>>>>>> Thanks to [1, 2], I was able to run Accumulo cluster on Google VMs
>>>>>> and with GCS instead of HDFS. And I used Google Dataproc to run Hadoop
jobs
>>>>>> on Accumulo. Almost everything was good until I've not faced some
>>>>>> connection issues with GCS. Quite often, the connection to GCS breaks
on
>>>>>> writing or closing WALs.
>>>>>>
>>>>>> To all,
>>>>>>
>>>>>> Does Accumulo have a specific write pattern, so that file system
may
>>>>>> not support it? Are there Accumulo properties which I can play with
to
>>>>>> adjust the write pattern?
>>>>>>
>>>>>> [1]: https://github.com/cybermaggedon/accumulo-gs
>>>>>> [2]: https://github.com/cybermaggedon/accumulo-docker
>>>>>>
>>>>>> Thank you!
>>>>>> Maxim
>>>>>>
>>>>>> On Tue, Jun 19, 2018 at 10:31 PM Geoffry Roberts <
>>>>>> threadedblue@gmail.com> wrote:
>>>>>>
>>>>>>> I tried running Accumulo on Google.  I first tried running it
on
>>>>>>> Google's pre-made Hadoop.  I found the various file paths one
must contend
>>>>>>> with are different on Google than on a straight download from
Apache.  It
>>>>>>> seems they moved things around.  To counter this, I installed
my own Hadoop
>>>>>>> along with Zookeeper and Accumulo on a Google node.  All went
well until
>>>>>>> one fine day when I could no longer log in.  It seems Google
had pushed out
>>>>>>> some changes over night that broke my client side Google Cloud
>>>>>>> installation.  Google referred the affected to a lengthy,
>>>>>>> easy-to-make-a-mistake procedure for resolving the issue.
>>>>>>>
>>>>>>> I decided life was too short for this kind of thing and switched
to
>>>>>>> Amazon.
>>>>>>>
>>>>>>> On Tue, Jun 19, 2018 at 7:34 AM, Maxim Kolchin <kolchinmax@gmail.com
>>>>>>> > wrote:
>>>>>>>
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> Does anyone have experience running Accumulo on top of Google
Cloud
>>>>>>>> Storage instead of HDFS? In [1] you can see some details
if you never heard
>>>>>>>> about this feature.
>>>>>>>>
>>>>>>>> I see some discussion (see [2], [3]) around this topic, but
it
>>>>>>>> looks to me that this isn't as popular as, I believe, should
be.
>>>>>>>>
>>>>>>>> [1]: https://cloud.google.com/dataproc/docs/concepts/connectors/
>>>>>>>> cloud-storage
>>>>>>>> [2]: https://github.com/apache/accumulo/issues/428
>>>>>>>> [3]: https://github.com/GoogleCloudPlatform/bigdata-interop/
>>>>>>>> issues/103
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Maxim
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> There are ways and there are ways,
>>>>>>>
>>>>>>> Geoffry Roberts
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> There are ways and there are ways,
>>>>>
>>>>> Geoffry Roberts
>>>>>
>>>>
>>>
>

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