Release Notes

Linux setup and configuration
25 Dell EMC PowerVault ME4 Series and Linux | 3924-BP-L
partitioning the volume wherever possible. This eases future volume expansion and reduces administration
overhead for maintaining the partitions.
If partitioning is required, it is recommended to align the partition on the 1 MB boundary. ME4 Series storage
uses internal disk pool chunk sizes ranging from 64k to 512k. The 1 MB boundary works well because it is a
multiple of the chunk size. Misalignment can result in extra I/Os to the volumes and degrades overall
performance. Either fdisk or parted can be used to create the partition. However, only parted can create
partitions larger than 2 TB. The parted method is described as follows.
1. Create a partition label.
# parted /dev/mapper/mpathb mklabel gpt
Warning: The existing disk label on /dev/mapper/mpathb will be destroyed
and all data on this disk will be lost. Do you want to continue?
Yes/No? Yes
Information: You may need to update /etc/fstab.
2. Create one partition with optimal alignment at 1 MB boundary.
# parted -a opt /dev/mapper/mpathb mkpart primary 2048s 100%
Information: You may need to update /etc/fstab.
3. Verify the partition alignment.
# parted /dev/mapper/mpathb align-check opt 1
1 aligned
3.4 Linux LVM
Linux Logical Volume Manager (LVM) is a common general-purpose storage manager included in all popular
Linux distributions. When working with LVM and ME4 Series storage, LVM mirroring is not necessary
because storage protection is already provided by the different RAID levels within the ME4 Series system. A
LVM volume group is a collection of one or more LUNs created on the ME4 volumes. Logical volumes are
created that span across the LUNs within the volume group.
3.4.1 LVM guidelines
Dell EMC recommends the following LVM guidelines:
• Use whole LUNs for logical volume groups.
• Create separate volume groups for different applications data. For example, if there are two
databases, separate the databases into logical volume groups. This simplifies management and
allows greater flexibility on array-based snapshots on individual applications.
• It is common to use two or more LUNs in a volume group to increase capacity and improve
performance. All LUNs in a logical volume group should be of the same size. To realize the full
performance benefit, evenly distribute the LUNs in different ME4 Series disk groups across the two
controllers.
• When using ME4 Series volume snapshots to protect the data in a logical volume group, the
snapshots must be taken on all LUNs in the same volume group at the same time to guarantee the
consistency of the data. It is a best practice to pause/stop the applications that are accessing the
LUNs before taking any snapshots.