Why is there only one instance of HLog.?

[Akash Ashok <th...@gmail.com>]

Hi,
    I was just wondering why is there only one instance of HLog? Wouldn't
this incur the overhead of synchronization when more than one region tries
to write to ? Why dnt we have an HLog per HRegion so that they Hregion's
writes are independent of each other? Plz do let me know if I am missing
somethin fundamental here.

Cheers,
Akash A

Re: Why is there only one instance of HLog.?

[Akash Ashok <th...@gmail.com>]

I just found the answer in "HBase: The Definitive Guide"

It quotes a quote from the BigTable paper -

" If we kept the commit log for each tablet in a separate log file, a very
large number of files would be written concurrently in GFS. Depending on the
underlying file system implementation on each GFS server, these writes could
cause a large number of disk seeks to write to the different physical log
files."

Cheers,
Akash A

On Tue, Aug 23, 2011 at 3:18 AM, Akash Ashok <th...@gmail.com> wrote:

> Hi,
>     I was just wondering why is there only one instance of HLog? Wouldn't
> this incur the overhead of synchronization when more than one region tries
> to write to ? Why dnt we have an HLog per HRegion so that they Hregion's
> writes are independent of each other? Plz do let me know if I am missing
> somethin fundamental here.
>
> Cheers,
> Akash A
>