RE: fdisk versus parted
- From: "Amaral, Rui" <Rui.Amaral@xxxxxxxxxxxxxxxx>
- To: "Walker, Jed S" <Jed_Walker@xxxxxxxxxxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 7 Feb 2013 10:11:01 -0500
One other thing is to turn of dos compatibility (this is version dependant so
confirm it with the version of fdisk you are using) - this would cause
cylinders (or sectors) to be overlapped so disable that.
Rui Amaral
Senior Oracle DBA
Oracle Database Engineering, TDBFG
E-Mail: rui.amaral@xxxxxxxxxxxxxxxx| Blackberry: 416-625-3280 |
-----Original Message-----
From: Walker, Jed S [mailto:Jed_Walker@xxxxxxxxxxxxxxxxx]
Sent: Thursday, February 07, 2013 10:09 AM
To: Amaral, Rui; oracle-l@xxxxxxxxxxxxx
Subject: RE: fdisk versus parted
Thanks Rui. That is probably the closest I'll get to confirm my thoughts. I
always use sectors. It would seem from this blog that maybe the people who
wrote the document at my company simply weren't aware that fdisk can be
switched to sectors.
>>Do not trust cylinder numbers reported by Linux **fdisk or parted**, because
>>both may be rounded to the nearest cylinder. As described in the Linux
>>specific section below, set units to sectors in both tools to verify
>>alignment.
I also check afterwards to ensure they are all correct:
fdisk -u -l /dev/mapper/ORA* | grep "/dev/mapper/ORA*" | grep -v "^Disk "
-----Original Message-----
From: Amaral, Rui [mailto:Rui.Amaral@xxxxxxxxxxxxxxxx]
Sent: Thursday, February 07, 2013 7:51 AM
To: Walker, Jed S; oracle-l@xxxxxxxxxxxxx
Subject: RE: fdisk versus parted
Look in the caveats section:
https://blogs.oracle.com/dlutz/entry/partition_alignment_guidelines_for_unified
Rui Amaral
Senior Oracle DBA
Oracle Database Engineering, TDBFG
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Walker, Jed S
Sent: Thursday, February 07, 2013 9:33 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: fdisk versus parted
We have a company document that says to not use fdisk to partition disks for
Oracle. It says to use parted or sfdisk. It says you can't guarantee alignment
with fdisk. My best guess is they didn't know about changing fdisk to sector
mode, or maybe the risk that you miss it on one, but we are not sure.
While building a new system I partitioned one LUN with fdisk and one with
parted (just for testing). Using fdisk they both show the same partition,
except for parted ended the partition earlier than fdisk, but if I'm looking
correctly not at an amount that would somehow make a difference. I also checked
the previous RAC I built with fdisk and saw the same result for all those
partitions as this fdisked one.
If anyone has any insight on this I'd appreciate it.
Here is what fdisk shows on the partitions. ORADATA01 was fdisk, ORADATA02 was
parted. Note the "End" sector. If I'm missing something obvious please let me
know.
[root@kdb-ch2-a1p ~]# fdisk /dev/mapper/ORADATA01
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): u
Changing display/entry units to sectors
Command (m for help): p
Disk /dev/mapper/ORADATA01: 107.4 GB, 107374510080 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209715840 sectors Units =
sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512
bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier:
0x215a6aaa
Device Boot Start End Blocks Id System
/dev/mapper/ORADATA01p1 2048 209715839 104856896 83 Linux
Command (m for help): q
[root@kdb-ch2-a1p ~]# fdisk /dev/mapper/ORADATA02
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): u
Changing display/entry units to sectors
Command (m for help): p
Disk /dev/mapper/ORADATA02: 107.4 GB, 107374510080 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209715840 sectors Units =
sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512
bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier:
0x00007076
Device Boot Start End Blocks Id System
/dev/mapper/ORADATA02p1 2048 209713151 104855552 83 Linux
Command (m for help): q
- Jed
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