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Posted to dev@hbase.apache.org by Andrew Purtell <ap...@apache.org> on 2010/01/12 21:05:50 UTC

revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Hi,

> Out of curiosity, since HDFS-127 was recently deemed harmful and
> reverted, will 0.20.3 still ship with patched version of Hadoop?  

Do you have a reference for that?

> Do you still recommend that patch be applied when running Hbase?

We needed that patch so long running HBase processes could ride over
intermittent DFS problems. Otherwise, the stream would become
unusable as soon as the errors accumulate, like the issue discusses.

It may still be an important patch for HBase even though there is
some problem with it otherwise. 

   - Andy



----- Original Message ----
> From: "Zlatin.Balevsky@barclayscapital.com" <Zl...@barclayscapital.com>
> To: hbase-dev@hadoop.apache.org
> Sent: Tue, January 12, 2010 11:34:49 AM
> Subject: RE: Vote on hbase-0.20.3RC1
> 
> Out of curiosity, since HDFS-127 was recently deemed harmful and
> reverted, will 0.20.3 still ship with patched version of Hadoop?  
> 
> Do you still recommend that patch be applied when running Hbase?
> 
> Zlatin
> _______________________________________________
> 
> This e-mail may contain information that is confidential, privileged or 
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> foregoing.  Barclays Capital is the investment banking division of Barclays Bank 
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> _______________________________________________



      


RE: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by Zl...@barclayscapital.com.

> Do you have a reference for that?

Comments in https://issues.apache.org/jira/browse/HDFS-784

According to 
http://issues.apache.org/jira/browse/HDFS-127?focusedCommentId=12798235&
page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#
action_12798235

it affects only the 0.20 branch.

Zlatin



----- Original Message ----
> From: "Zlatin.Balevsky@barclayscapital.com" 
> <Zl...@barclayscapital.com>
> To: hbase-dev@hadoop.apache.org
> Sent: Tue, January 12, 2010 11:34:49 AM
> Subject: RE: Vote on hbase-0.20.3RC1
> 
> Out of curiosity, since HDFS-127 was recently deemed harmful and 
> reverted, will 0.20.3 still ship with patched version of Hadoop?
> 
> Do you still recommend that patch be applied when running Hbase?
> 
> Zlatin
> _______________________________________________
> 
> This e-mail may contain information that is confidential, privileged 
> or otherwise protected from disclosure. If you are not an intended 
> recipient of this e-mail, do not duplicate or redistribute it by any 
> means. Please delete it and any attachments and notify the sender that
you have received it in error.
> Unless specifically indicated, this e-mail is not an offer to buy or 
> sell or a solicitation to buy or sell any securities, investment 
> products or other financial product or service, an official 
> confirmation of any transaction, or an official statement of Barclays.

> Any views or opinions presented are solely those of the author and do 
> not necessarily represent those of Barclays. This e-mail is subject to
terms available at the following link:
> www.barcap.com/emaildisclaimer. By messaging with Barclays you consent

> to the foregoing.  Barclays Capital is the investment banking division

> of Barclays Bank PLC, a company registered in England (number 1026167)

> with its registered office at 1 Churchill Place, London, E14 5HP.  
> This email may relate to or be sent from other members of the Barclays
Group.
> _______________________________________________



      

_______________________________________________

This e-mail may contain information that is confidential, privileged or otherwise protected from disclosure. If you are not an intended recipient of this e-mail, do not duplicate or redistribute it by any means. Please delete it and any attachments and notify the sender that you have received it in error. Unless specifically indicated, this e-mail is not an offer to buy or sell or a solicitation to buy or sell any securities, investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Barclays. Any views or opinions presented are solely those of the author and do not necessarily represent those of Barclays. This e-mail is subject to terms available at the following link: www.barcap.com/emaildisclaimer. By messaging with Barclays you consent to the foregoing.  Barclays Capital is the investment banking division of Barclays Bank PLC, a company registered in England (number 1026167) with its registered office at 1 Churchill Place, London, E14 5HP.  This email may relate to or be sent from other members of the Barclays Group.
_______________________________________________

Re: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by Dhruba Borthakur <dh...@gmail.com>.
> If we have to, we can call a new API which tells us when we dip below
wantedreplicas and close the file (if we can per Hairong's comment) and
reopen anew.

Yes, that's the idea.

Re: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by stack <st...@duboce.net>.
Is this so we can avoid having the DFSClient fall into an infinite loop in
the case where there are no more replicas, the reason for backing out
hdfs-127 from 0.20 branch?

If we have to, we can call a new API which tells us when we dip below wanted
replicas and close the file (if we can per Hairong's comment) and reopen a
new.  Any danger of running out of replicas in between calls to the new
method?

(But I like Ryan's comment up in the issue best, that DFSClient just handles
it for us)

St.Ack


On Tue, Jan 12, 2010 at 3:11 PM, Dhruba Borthakur <dh...@gmail.com> wrote:

> Here is a JIRA that I opened after some offline discussion with Joydeep.
>
> http://issues.apache.org/jira/browse/HDFS-826
>
> This will allow a client  (e.g. Region Server) to periodically query the
> dfs
> file handle to retrieve the number of currently active replicas. if the
> number of replicas falls below 3, then the region server could close the
> Hfile and open a new hfile. what do people think about that approach?
>
> thanks,
> dhruba
>
>
> On Tue, Jan 12, 2010 at 12:28 PM, stack <st...@duboce.net> wrote:
>
> > (Andrew, see hdfs-127 on its tail for update)
> >
> > Zlatin:
> >
> > IMO, its better keeping hdfs-127.  You actually can't run an hbase
> cluster
> > of any size without it.  The rate at which files go bad -- dfsclient
> turns
> > into a zombie after accumulating 3 errors after any 3 transient failures
> --
> > does the cluster a mortal blow.  The scenario where all replicas go away
> is
> > relatively rare and probably indicative of a more serious hdfs issue
> > though,
> > according to the issue, when it happens, its ugly with dfsclient going
> into
> > an infinite loop.
> >
> > St.Ack
> >
> >
> > On Tue, Jan 12, 2010 at 12:05 PM, Andrew Purtell <apurtell@apache.org
> > >wrote:
> >
> > > Hi,
> > >
> > > > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > > > reverted, will 0.20.3 still ship with patched version of Hadoop?
> > >
> > > Do you have a reference for that?
> > >
> > > > Do you still recommend that patch be applied when running Hbase?
> > >
> > > We needed that patch so long running HBase processes could ride over
> > > intermittent DFS problems. Otherwise, the stream would become
> > > unusable as soon as the errors accumulate, like the issue discusses.
> > >
> > > It may still be an important patch for HBase even though there is
> > > some problem with it otherwise.
> > >
> > >   - Andy
> > >
> > >
> > >
> > > ----- Original Message ----
> > > > From: "Zlatin.Balevsky@barclayscapital.com" <
> > > Zlatin.Balevsky@barclayscapital.com>
> > > > To: hbase-dev@hadoop.apache.org
> > > > Sent: Tue, January 12, 2010 11:34:49 AM
> > > > Subject: RE: Vote on hbase-0.20.3RC1
> > > >
> > > > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > > > reverted, will 0.20.3 still ship with patched version of Hadoop?
> > > >
> > > > Do you still recommend that patch be applied when running Hbase?
> > > >
> > > > Zlatin
> > > > _______________________________________________
> > > >
> > > > This e-mail may contain information that is confidential, privileged
> or
> > > > otherwise protected from disclosure. If you are not an intended
> > recipient
> > > of
> > > > this e-mail, do not duplicate or redistribute it by any means. Please
> > > delete it
> > > > and any attachments and notify the sender that you have received it
> in
> > > error.
> > > > Unless specifically indicated, this e-mail is not an offer to buy or
> > sell
> > > or a
> > > > solicitation to buy or sell any securities, investment products or
> > other
> > > > financial product or service, an official confirmation of any
> > > transaction, or an
> > > > official statement of Barclays. Any views or opinions presented are
> > > solely those
> > > > of the author and do not necessarily represent those of Barclays.
> This
> > > e-mail is
> > > > subject to terms available at the following link:
> > > > www.barcap.com/emaildisclaimer. By messaging with Barclays you
> consent
> > > to the
> > > > foregoing.  Barclays Capital is the investment banking division of
> > > Barclays Bank
> > > > PLC, a company registered in England (number 1026167) with its
> > registered
> > > office
> > > > at 1 Churchill Place, London, E14 5HP.  This email may relate to or
> be
> > > sent from
> > > > other members of the Barclays Group.
> > > > _______________________________________________
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
> --
> Connect to me at http://www.facebook.com/dhruba
>

Re: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by Ryan Rawson <ry...@gmail.com>.
I don't get it, why would HBase need to reopen the hfile?  Has it gone
bad? If it has, why would reopening help?

Or are you talking about resetting the state in the DFSClient by
forcing the end-client to know more about the namenode/client
internals?

This doesn't sound right... the DFSClient abstraction should leak this badly...


On Tue, Jan 12, 2010 at 3:11 PM, Dhruba Borthakur <dh...@gmail.com> wrote:
> Here is a JIRA that I opened after some offline discussion with Joydeep.
>
> http://issues.apache.org/jira/browse/HDFS-826
>
> This will allow a client  (e.g. Region Server) to periodically query the dfs
> file handle to retrieve the number of currently active replicas. if the
> number of replicas falls below 3, then the region server could close the
> Hfile and open a new hfile. what do people think about that approach?
>
> thanks,
> dhruba
>
>
> On Tue, Jan 12, 2010 at 12:28 PM, stack <st...@duboce.net> wrote:
>
>> (Andrew, see hdfs-127 on its tail for update)
>>
>> Zlatin:
>>
>> IMO, its better keeping hdfs-127.  You actually can't run an hbase cluster
>> of any size without it.  The rate at which files go bad -- dfsclient turns
>> into a zombie after accumulating 3 errors after any 3 transient failures --
>> does the cluster a mortal blow.  The scenario where all replicas go away is
>> relatively rare and probably indicative of a more serious hdfs issue
>> though,
>> according to the issue, when it happens, its ugly with dfsclient going into
>> an infinite loop.
>>
>> St.Ack
>>
>>
>> On Tue, Jan 12, 2010 at 12:05 PM, Andrew Purtell <apurtell@apache.org
>> >wrote:
>>
>> > Hi,
>> >
>> > > Out of curiosity, since HDFS-127 was recently deemed harmful and
>> > > reverted, will 0.20.3 still ship with patched version of Hadoop?
>> >
>> > Do you have a reference for that?
>> >
>> > > Do you still recommend that patch be applied when running Hbase?
>> >
>> > We needed that patch so long running HBase processes could ride over
>> > intermittent DFS problems. Otherwise, the stream would become
>> > unusable as soon as the errors accumulate, like the issue discusses.
>> >
>> > It may still be an important patch for HBase even though there is
>> > some problem with it otherwise.
>> >
>> >   - Andy
>> >
>> >
>> >
>> > ----- Original Message ----
>> > > From: "Zlatin.Balevsky@barclayscapital.com" <
>> > Zlatin.Balevsky@barclayscapital.com>
>> > > To: hbase-dev@hadoop.apache.org
>> > > Sent: Tue, January 12, 2010 11:34:49 AM
>> > > Subject: RE: Vote on hbase-0.20.3RC1
>> > >
>> > > Out of curiosity, since HDFS-127 was recently deemed harmful and
>> > > reverted, will 0.20.3 still ship with patched version of Hadoop?
>> > >
>> > > Do you still recommend that patch be applied when running Hbase?
>> > >
>> > > Zlatin
>> > > _______________________________________________
>> > >
>> > > This e-mail may contain information that is confidential, privileged or
>> > > otherwise protected from disclosure. If you are not an intended
>> recipient
>> > of
>> > > this e-mail, do not duplicate or redistribute it by any means. Please
>> > delete it
>> > > and any attachments and notify the sender that you have received it in
>> > error.
>> > > Unless specifically indicated, this e-mail is not an offer to buy or
>> sell
>> > or a
>> > > solicitation to buy or sell any securities, investment products or
>> other
>> > > financial product or service, an official confirmation of any
>> > transaction, or an
>> > > official statement of Barclays. Any views or opinions presented are
>> > solely those
>> > > of the author and do not necessarily represent those of Barclays. This
>> > e-mail is
>> > > subject to terms available at the following link:
>> > > www.barcap.com/emaildisclaimer. By messaging with Barclays you consent
>> > to the
>> > > foregoing.  Barclays Capital is the investment banking division of
>> > Barclays Bank
>> > > PLC, a company registered in England (number 1026167) with its
>> registered
>> > office
>> > > at 1 Churchill Place, London, E14 5HP.  This email may relate to or be
>> > sent from
>> > > other members of the Barclays Group.
>> > > _______________________________________________
>> >
>> >
>> >
>> >
>> >
>> >
>>
>
>
>
> --
> Connect to me at http://www.facebook.com/dhruba
>

Re: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by Dhruba Borthakur <dh...@gmail.com>.
Here is a JIRA that I opened after some offline discussion with Joydeep.

http://issues.apache.org/jira/browse/HDFS-826

This will allow a client  (e.g. Region Server) to periodically query the dfs
file handle to retrieve the number of currently active replicas. if the
number of replicas falls below 3, then the region server could close the
Hfile and open a new hfile. what do people think about that approach?

thanks,
dhruba


On Tue, Jan 12, 2010 at 12:28 PM, stack <st...@duboce.net> wrote:

> (Andrew, see hdfs-127 on its tail for update)
>
> Zlatin:
>
> IMO, its better keeping hdfs-127.  You actually can't run an hbase cluster
> of any size without it.  The rate at which files go bad -- dfsclient turns
> into a zombie after accumulating 3 errors after any 3 transient failures --
> does the cluster a mortal blow.  The scenario where all replicas go away is
> relatively rare and probably indicative of a more serious hdfs issue
> though,
> according to the issue, when it happens, its ugly with dfsclient going into
> an infinite loop.
>
> St.Ack
>
>
> On Tue, Jan 12, 2010 at 12:05 PM, Andrew Purtell <apurtell@apache.org
> >wrote:
>
> > Hi,
> >
> > > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > > reverted, will 0.20.3 still ship with patched version of Hadoop?
> >
> > Do you have a reference for that?
> >
> > > Do you still recommend that patch be applied when running Hbase?
> >
> > We needed that patch so long running HBase processes could ride over
> > intermittent DFS problems. Otherwise, the stream would become
> > unusable as soon as the errors accumulate, like the issue discusses.
> >
> > It may still be an important patch for HBase even though there is
> > some problem with it otherwise.
> >
> >   - Andy
> >
> >
> >
> > ----- Original Message ----
> > > From: "Zlatin.Balevsky@barclayscapital.com" <
> > Zlatin.Balevsky@barclayscapital.com>
> > > To: hbase-dev@hadoop.apache.org
> > > Sent: Tue, January 12, 2010 11:34:49 AM
> > > Subject: RE: Vote on hbase-0.20.3RC1
> > >
> > > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > > reverted, will 0.20.3 still ship with patched version of Hadoop?
> > >
> > > Do you still recommend that patch be applied when running Hbase?
> > >
> > > Zlatin
> > > _______________________________________________
> > >
> > > This e-mail may contain information that is confidential, privileged or
> > > otherwise protected from disclosure. If you are not an intended
> recipient
> > of
> > > this e-mail, do not duplicate or redistribute it by any means. Please
> > delete it
> > > and any attachments and notify the sender that you have received it in
> > error.
> > > Unless specifically indicated, this e-mail is not an offer to buy or
> sell
> > or a
> > > solicitation to buy or sell any securities, investment products or
> other
> > > financial product or service, an official confirmation of any
> > transaction, or an
> > > official statement of Barclays. Any views or opinions presented are
> > solely those
> > > of the author and do not necessarily represent those of Barclays. This
> > e-mail is
> > > subject to terms available at the following link:
> > > www.barcap.com/emaildisclaimer. By messaging with Barclays you consent
> > to the
> > > foregoing.  Barclays Capital is the investment banking division of
> > Barclays Bank
> > > PLC, a company registered in England (number 1026167) with its
> registered
> > office
> > > at 1 Churchill Place, London, E14 5HP.  This email may relate to or be
> > sent from
> > > other members of the Barclays Group.
> > > _______________________________________________
> >
> >
> >
> >
> >
> >
>



-- 
Connect to me at http://www.facebook.com/dhruba

Re: revert of HDFS-127? (was Re: Vote on hbase-0.20.3RC1)

Posted by stack <st...@duboce.net>.
(Andrew, see hdfs-127 on its tail for update)

Zlatin:

IMO, its better keeping hdfs-127.  You actually can't run an hbase cluster
of any size without it.  The rate at which files go bad -- dfsclient turns
into a zombie after accumulating 3 errors after any 3 transient failures --
does the cluster a mortal blow.  The scenario where all replicas go away is
relatively rare and probably indicative of a more serious hdfs issue though,
according to the issue, when it happens, its ugly with dfsclient going into
an infinite loop.

St.Ack


On Tue, Jan 12, 2010 at 12:05 PM, Andrew Purtell <ap...@apache.org>wrote:

> Hi,
>
> > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > reverted, will 0.20.3 still ship with patched version of Hadoop?
>
> Do you have a reference for that?
>
> > Do you still recommend that patch be applied when running Hbase?
>
> We needed that patch so long running HBase processes could ride over
> intermittent DFS problems. Otherwise, the stream would become
> unusable as soon as the errors accumulate, like the issue discusses.
>
> It may still be an important patch for HBase even though there is
> some problem with it otherwise.
>
>   - Andy
>
>
>
> ----- Original Message ----
> > From: "Zlatin.Balevsky@barclayscapital.com" <
> Zlatin.Balevsky@barclayscapital.com>
> > To: hbase-dev@hadoop.apache.org
> > Sent: Tue, January 12, 2010 11:34:49 AM
> > Subject: RE: Vote on hbase-0.20.3RC1
> >
> > Out of curiosity, since HDFS-127 was recently deemed harmful and
> > reverted, will 0.20.3 still ship with patched version of Hadoop?
> >
> > Do you still recommend that patch be applied when running Hbase?
> >
> > Zlatin
> > _______________________________________________
> >
> > This e-mail may contain information that is confidential, privileged or
> > otherwise protected from disclosure. If you are not an intended recipient
> of
> > this e-mail, do not duplicate or redistribute it by any means. Please
> delete it
> > and any attachments and notify the sender that you have received it in
> error.
> > Unless specifically indicated, this e-mail is not an offer to buy or sell
> or a
> > solicitation to buy or sell any securities, investment products or other
> > financial product or service, an official confirmation of any
> transaction, or an
> > official statement of Barclays. Any views or opinions presented are
> solely those
> > of the author and do not necessarily represent those of Barclays. This
> e-mail is
> > subject to terms available at the following link:
> > www.barcap.com/emaildisclaimer. By messaging with Barclays you consent
> to the
> > foregoing.  Barclays Capital is the investment banking division of
> Barclays Bank
> > PLC, a company registered in England (number 1026167) with its registered
> office
> > at 1 Churchill Place, London, E14 5HP.  This email may relate to or be
> sent from
> > other members of the Barclays Group.
> > _______________________________________________
>
>
>
>
>
>