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Message-ID: <CAOiN93kV079jkdzY-R7jMVGQq4nN4c-sdswCq-XRaOpZm=ttwA@mail.gmail.com>
Date: Tue, 30 Oct 2012 18:27:52 +0530
From: Ashish Sangwan <ashishsangwan2@...il.com>
To: tytso@....edu, adilger@...ger.ca, sandeen@...hat.com,
Namjae Jeon <linkinjeon@...il.com>
Cc: linux-ext4@...r.kernel.org
Subject: How to use new "native 4k sector sized" HDD with ext4
We have a 2TB HDD having native 4k sector size but emulated as 512bytes.
And we want to use this device with sector size 4k and not 512bytes.
In mkfs.xfs there is option "-s", using which, one can set the sector size.
What is the use case of this option?
Also, such option is not present for ext4. So, apart from aligining the
partition on multiple of 8 sector numbers do we have to do something else
for using 4k sectors?
We measured the write performance of XFS/EXT4 with sector size 512bytes and 4KB.
XFS With 512 byte sector size=>
RecSize WriteSpeed RanReadSpeed RanWriteSpeed
524288 22.12MB/sec 0.00MB/sec 0.00MB/sec
262144 18.87MB/sec 0.00MB/sec 0.00MB/sec
131072 18.25MB/sec 0.00MB/sec 0.00MB/sec
65536 18.90MB/sec 0.00MB/sec 0.00MB/sec
32768 23.26MB/sec 0.00MB/sec 0.00MB/sec
16384 18.21MB/sec 0.00MB/sec 0.00MB/sec
8192 21.23MB/sec 0.00MB/sec 0.00MB/sec
4096 20.58MB/sec 0.00MB/sec 0.00MB/sec
XFS after setting 4KB sector size (-s size 4096) =>
RecSize WriteSpeed RanReadSpeed RanWriteSpeed
524288 21.93MB/sec 0.00MB/sec 0.00MB/sec
262144 28.49MB/sec 0.00MB/sec 0.00MB/sec
131072 25.64MB/sec 0.00MB/sec 0.00MB/sec
65536 24.27MB/sec 0.00MB/sec 0.00MB/sec
32768 26.39MB/sec 0.00MB/sec 0.00MB/sec
16384 28.49MB/sec 0.00MB/sec 0.00MB/sec
8192 22.83MB/sec 0.00MB/sec 0.00MB/sec
4096 24.88MB/sec 0.00MB/sec 0.00MB/sec
Ext4 with default mkfs.ext4 options =>
RecSize WriteSpeed RanReadSpeed RanWriteSpeed
524288 31.95MB/sec 0.00MB/sec 0.00MB/sec
262144 26.88MB/sec 0.00MB/sec 0.00MB/sec
131072 23.04MB/sec 0.00MB/sec 0.00MB/sec
65536 25.91MB/sec 0.00MB/sec 0.00MB/sec
32768 24.69MB/sec 0.00MB/sec 0.00MB/sec
16384 24.27MB/sec 0.00MB/sec 0.00MB/sec
8192 32.05MB/sec 0.00MB/sec 0.00MB/sec
4096 30.21MB/sec 0.00MB/sec 0.00MB/sec
Ext4 performed little better than XFS (-s size 4096).
Seeing this, we are tempted to believe that ext4 is already
using 4k sectors.
Is there any way to make sure that ext4 is indeed using 4k sectors?
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