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October 26th, 2016 06:00
disk alignment warning - Unity300 and Redhat Linux
I am getting an error "alignment is offset by 512 bytes. This may result in very poor performance, (re)-partitioning suggested" when I format any LUN from UNITY300 storage on Redhat Linux. But LUN is already aligned with fdisk command.
Environment details as follows -
1. A direct attached FC Unity300 and HP DL580G9 server + Redhat (RHEL) 7.2
2. FAST cache & FASTVP is enabled
Any storage LUN irrespective of the size giving this error when try to format using mkfs.ext3.
The LUN is already aligned b fdisk/parted and verified by parted tool.
Please see below my steps and command output -
#multipath -ll
mpathd (36006016006214200f43f0f584ce28280) dm-3 DGC ,VRAID
size=300G features='2 queue_if_no_path retain_attached_hw_handler' hwhandler='1 alua' wp=rw
|-+- policy='service-time 0' prio=50 status=active
| `- 1:0:0:0 sdc 8:32 active ready running
`-+- policy='service-time 0' prio=10 status=enabled
`- 3:0:0:0 sdd 8:48 active ready running
# fdisk /dev/mapper/mpathd
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xa0d6a56b.
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (65535-629145599, default 65535):
Using default value 65535
Last sector, +sectors or +size{K,M,G} (65535-629145599, default 629145599):
Using default value 629145599
Partition 1 of type Linux and of size 300 GiB is set
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
# partprobe /dev/mapper/mpathd
# mkfs.ext3 /dev/mapper/mpathd1
mke2fs 1.42.9 (28-Dec-2013)
/dev/mapper/mpathd1 alignment is offset by 512 bytes.
This may result in very poor performance, (re)-partitioning suggested.
Discarding device blocks: done
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=2 blocks, Stripe width=8191 blocks
19660800 inodes, 78635008 blocks
3931750 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
2400 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done