ext3/ext4 physical block size view – Managing your servers can streamline the performance of your team by allowing them to complete complex tasks faster. Plus, it can enable them to detect problems early on before they get out of hand and compromise your business. As a result, the risk of experiencing operational setbacks is drastically lower.
But the only way to make the most of your server management is to perform it correctly. And to help you do so, this article will share nine tips on improving your server management and fix some problem about linux, filesystems, linux-kernel, sles, .
I’m using a suse 11 server with xfs and using “xfs_info /srv” command i seen this.
xfs_info /srv/ meta-data=/dev/mapper/vg01-srvvol isize=256 agcount=38, agsize=1964032 blks = sectsz=512 attr=2 data = bsize=4096 blocks=73367552, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal bsize=4096 blocks=3836, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
So i think xfs knows the size of underline disk sectsz, but I’m using now a disk with sectsz of 512 bytes, but my question is, how can find this kind of information using ext3/ext4 filesystem?
Because i would like to try to use a new disk with sectsz of 4096 and be sure, ext3/ext4 uses the underline sectsz.
This is the output of xfs_info using one new ssd with physical block size 4096:
xfs_info /dev/mapper/vg00-logvol meta-data=/dev/mapper/vg00-logvol isize=256 agcount=16, agsize=7144576 blks = sectsz=4096 attr=2, projid32bit=0 data = bsize=4096 blocks=114313216, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 log =internal bsize=4096 blocks=55817, version=2 = sectsz=4096 sunit=1 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0
$ sudo tune2fs -l /dev/vda1 tune2fs 1.42.8 (20-Jun-2013) Filesystem volume name: <none> ... Free inodes: 127696 First block: 1 Block size: 1024 Fragment size: 1024 Reserved GDT blocks: 256 Blocks per group: 8192 ...
First, find the underlying
ls -l /dev/mapper/vg01-srvvol
lrwxrwxrwx 1 root root 7 Jan 28 14:32 /dev/mapper/vg01-srvvol -> ../dm-0
dm-1, etc and see here:
The only reliable way to determine the real physical block size is by querying the disk directly with
hdparm -I /dev/sdX | grep Physical
All linux tools like
fdisk, also the kernel (via the value provided in /proc) output 512 Bytes for disks I have which are denoted 4K by
hdparm. (5 HDDs tested, with two being 4K ones.)