Choosing the appropriate Linux file system for HDFS deployment
The Hadoop Distributed File System is platform independent and can
function on top of any underlying file system and Operating System.
Linux offers a variety of file system choices, each with caveats that
have an impact on HDFS.
As a general best practice, if you are mounting disks solely for Hadoop data, disable ‘noatime’. This speeds up reads for files.
There are three Linux file system options that are popular to choose from:
Yahoo uses the ext3 file system for its Hadoop deployments. ext3 is
also the default filesystem choice for many popular Linux OS flavours.
Since HDFS on ext3 has been publicly tested on Yahoo’s cluster it makes
for a safe choice for the underlying file system.
ext4 is the successor to ext3. ext4 has better performance with large
files. ext4 also introduced delayed allocation of data, which adds a
bit more risk with unplanned server outages while decreasing
fragmentation and improving performance.
XFS offers better disk space utilization than ext3 and has much
quicker disk formatting times than ext3. This means that it is quicker
to get started with a data node using XFS.
Most often performance of a Hadoop cluster will not be constrained by
disk speed – I/O and RAM limitations will be more important. ext3 has
been extensively tested with Hadoop and is currently the stable option
to go with. ext4 and xfs can be considered as well and they give some