Disk partitioning unit ?

Latest response

Hi!

I would like to ask question regarding to the unit for disk partitioning for RHEL 7.1.
I am bit confused with this so I appreciate if someone can help me.

In the installation guide P 162 it says ,
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/pdf/Installation_Guide/Red_Hat_Enterprise_Linux-7-Installation_Guide-en-US.pdf

"Desired Capacity - enter the desired size of the partition. You can use common size units
such as kilobytes, megabytes, gigabytes, or terabytes. Megabytes are the default option if you do
not specify any unit"

In the example screen shot, for /boot partition,
when you actually add the partition, the unit is shown in "MiB" which stands for Mebibyte.

My question is , before starting the installation,
should you design the filesystem sizing in "Megabyte" or "Mebityte"?

Attachments

Responses

I cannot find the reference now, but device-mapper runs into performance issues if a device does not align to page size (4KiB). dm will split all I/Os to the device into smaller sub-page sizes.

Personally I align all my storage to MiB (1024 KiB or 2048 sectors) at both start and end, and only refer to storage in powers-of-two.

Powers-of-ten are good for fudging marketing figures and not much else ;)

NetApp and VMware used to maintain good documents on the subject. The alignment issue in virtualization environments tends to be of even greater importance than in physical environments (since multiple "hosts" share a common data-store and multiple mis-aligned I/O setups can really thrash a datastore).

Stephen , Jamie, Tom.

Thank you for the comments!

Jamie's comment clarified my point.

Also, from the point of view that since filesystem uses binary units for the block size,
I guess I need to design the sizing in binary units before installing. In this sense,
I could have clear understanding before the installation and after the installation.

Close

Welcome! Check out the Getting Started with Red Hat page for quick tours and guides for common tasks.