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Linux Logical Volume Manager (LVM) is a common general-purpose storage manager in all popular Linux distributions. Since ASM does not support storing Oracle software, the software must be installed on a Linux file system that can be configured on top of LVM. LVM mirroring is not necessary because Dell Unity systems provide storage protection. Multiple LUNs can be grouped into a single LVM volume group. Then logical volumes must be created that span across these LUNs. When taking Dell Unity system snapshots on a multi-LUN volume group, ensure the LUNs are configured in a consistency group.
A file system is created on a logical volume where the Oracle binary is installed. More space can be added to the volume groups, logical volumes, and file systems either by adding new LUNs or by expanding existing LUNS in the volume groups. Once volume groups and logical volumes are expanded, the file systems can be resized to the newly added space. LVM and many file systems, such as ext4 and xfs, allow on-demand expansion without taking down the applications.
Unlike ASM, administrators must configure LVM striping, and data is not rebalanced when extending the volume group.
When initializing LUNs in LVM, use the --dataalignment argument to indicate the alignment starts at 1 M.
The following example shows the tasks to create an Oracle software file system on LVM:
# pvcreate --dataalignment 1m /dev/mapper/orabin-rac
# vgcreate vgoracle /dev/mapper/orabin-rac
# lvcreate –L 50g –n lv-oracle-bin vgoracle
# mkfs.xfs /dev/vgoracle/lv-oracle-bin (for xfs)
# mkfs.ext4 /dev/vgoracle/lv-oracle-bin (for ext4)
Note: if --dataalignment is not specified, mkfs might report a warning message (see below). Reinitialize the LUN with --dataalignment to ensure proper alignment.
Misalignment warning for mkfs.xfs:
warning: device is not properly aligned /dev/vgoracle/lv-oracle-logs
Use -f to force usage of a misaligned device
Misalignment warning for mkfs.ext4:
mke2fs 1.42.9 (28-Dec-2013)
/dev/vgoracle/lv-oracle-bin alignment is offset by 512 bytes.
This may result in very poor performance, (re)-partitioning suggested.