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From Jay Kreps <jay.kr...@gmail.com>
Subject Re: new log.dirs property (as opposed to log.dir)
Date Thu, 15 Aug 2013 14:10:16 GMT
I believe either should work. The broker has a record of what it should have in zk and will
recreate any missing logs. Try it to make sure though.

Sent from my iPhone

On Aug 15, 2013, at 12:52 AM, Jason Rosenberg <jbr@squareup.com> wrote:

> Ok, that makes sense that the broker will shut itself down.
> 
> If we bring it back up, can this be with an altered set of log.dirs?  Will
> the destroyed partitions get rebuilt on a new log.dir?  Or do we have to
> bring it back up with a new or repaired disk, matching the old log.dir, in
> order for those replicas to be rebuilt?
> 
> Jason
> 
> 
> On Wed, Aug 14, 2013 at 4:16 PM, Jay Kreps <jay.kreps@gmail.com> wrote:
> 
>> If you get a disk error that results in an IOException the broker will
>> shut itself down. You would then have the option of replacing the disk or
>> deleting that data directory from the list. When the broker is brought back
>> up the intact partitions will quickly catch up and be online; the destroyed
>> partitions will have to fully rebuild off the other replicas and will take
>> a little longer but will automatically come back online once they have
>> restored off the replicas.
>> 
>> -jay
>> 
>> Sent from my iPhone
>> 
>> On Aug 14, 2013, at 1:49 PM, Jason Rosenberg <jbr@squareup.com> wrote:
>> 
>>> I'm getting ready to try out this configuration (use multiple disks, no
>>> RAID, per broker).  One concern is the procedure for recovering if there
>> is
>>> a disk failure.
>>> 
>>> If a disk fails, will the broker go offline, or will it continue serving
>>> partitions on its remaining good disks?  And if so, is there a procedure
>>> for moving the partitions that were on the failed disk, but not
>> necessarily
>>> all the others on that broker?
>>> 
>>> Jason
>>> 
>>> 
>>> On Thu, Jun 20, 2013 at 3:15 PM, Jason Rosenberg <jbr@squareup.com>
>> wrote:
>>> 
>>>> yeah, that would work!
>>>> 
>>>> 
>>>> On Thu, Jun 20, 2013 at 1:20 PM, Jay Kreps <jay.kreps@gmail.com> wrote:
>>>> 
>>>>> Yeah we didn't go as far as adding weighting or anything like that--I
>>>>> think we'd be open to a patch that did that as long as it was
>>>>> optional. In the short term you can obviously add multiple directories
>>>>> on the same disk to increase its share.
>>>>> 
>>>>> -Jay
>>>>> 
>>>>> On Thu, Jun 20, 2013 at 12:59 PM, Jason Rosenberg <jbr@squareup.com>
>>>>> wrote:
>>>>>> This sounds like a great idea, to just disks as "just a bunch of
>> disks"
>>>>> or
>>>>>> JBOD.....hdfs works well this way.
>>>>>> 
>>>>>> Do all the disks need to be the same size, to use them evenly?  Since
>> it
>>>>>> will allocate partitions randomly?
>>>>>> 
>>>>>> It would be nice if you had 2 disks, with one twice as large as the
>>>>> other,
>>>>>> if the larger would be twice as likely to receive partitions as the
>>>>> smaller
>>>>>> one, etc.
>>>>>> 
>>>>>> I suppose this goes into my earlier question to the list, vis-a-vis
>>>>>> heterogeneous brokers (e.g. utilize brokers with different sized
>>>>> storage,
>>>>>> using some sort of weighting scheme, etc.).
>>>>>> 
>>>>>> Jason
>>>>>> 
>>>>>> 
>>>>>> On Thu, Jun 20, 2013 at 11:07 AM, Jay Kreps <jay.kreps@gmail.com>
>>>>> wrote:
>>>>>> 
>>>>>>> The intention is to allow the use of multiple disks without RAID
or
>>>>>>> logical volume management. We have found that there are a lot
of
>>>>>>> downsides to RAID--in particular a huge throughput hit. Since
we
>>>>>>> already have a parallelism model due to partitioning and a fault
>>>>>>> tolerance model with replication RAID doesn't actually buy much.
With
>>>>>>> this feature you can directly mount multiple disks as their own
>>>>>>> directory and the server will randomly assign partitions to them.
>>>>>>> 
>>>>>>> Obviously this will only work well if there are enough
>> high-throughput
>>>>>>> partitions to make load balance evenly (e.g. if you have only
one big
>>>>>>> partition per server then this isn't going to work).
>>>>>>> 
>>>>>>> -Jay
>>>>>>> 
>>>>>>> On Wed, Jun 19, 2013 at 11:01 PM, Jason Rosenberg <jbr@squareup.com>
>>>>>>> wrote:
>>>>>>>> is it possible for a partition to have multiple replicas
on
>> different
>>>>>>>> directories on the same broker?  (hopefully no!)
>>>>>>>> 
>>>>>>>> 
>>>>>>>> On Wed, Jun 19, 2013 at 10:47 PM, Jun Rao <junrao@gmail.com>
wrote:
>>>>>>>> 
>>>>>>>>> It takes a comma separated list and partition replicas
are randomly
>>>>>>>>> distributed to the list.
>>>>>>>>> 
>>>>>>>>> Thanks,
>>>>>>>>> 
>>>>>>>>> Jun
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> On Wed, Jun 19, 2013 at 10:25 PM, Jason Rosenberg <
>> jbr@squareup.com
>>>>>> 
>>>>>>>>> wrote:
>>>>>>>>> 
>>>>>>>>>> In the 0.8 config, log.dir is now log.dirs.  It looks
like the
>>>>>>> singular
>>>>>>>>>> log.dir is still supported, but under the covers
the property is
>>>>>>>>> log.dirs.
>>>>>>>>>> 
>>>>>>>>>> I'm curious, does this take a comma separated list
of directories?
>>>>>>> The
>>>>>>>>> new
>>>>>>>>>> config page just says:
>>>>>>>>>> "The directories in which the log data is kept"
>>>>>>>>>> 
>>>>>>>>>> Also, how does kafka handle multiple directories?
 Does it treat
>>>>> each
>>>>>>>>>> directory as a separate replica partition, or what?
>>>>>>>>>> 
>>>>>>>>>> Jason
>> 

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