File System Layout Calculator

Updated -

This app is designed to help you determine the optimal parameters for creating ext3/ext4/xfs file systems. When you input information about your current or planned storage, we'll generate a command to create a file system on given RAID storage.

To use this app, pick or fill a proper option for the file system you are going to create, then click the Calculate button. A command will be shown on the upper right part of the page. Simply copy that generated command and execute it as the root user to create your file system.

If you're not sure about a field, hover your mouse pointer over the question mark (?) beside it to see a brief explanation, or you can scroll down to the bottom of the screen to read a summary of all options.

Was this helpful?

We appreciate your feedback. Leave a comment if you would like to provide more detail.
It looks like we have some work to do. Leave a comment to let us know how we could improve.

Get notified when this content is updated



Subscriber exclusive content

An active Red Hat subscription is required to participate.

Log In

Output of this tool is incorrect for raid level = 6, fs type =XFS, physical disks=12, raid chunk size =64 , bs=4096

SU would be "64k" or "16" (blocks). NOT "16k!"

mkfs.xfs -b 4096 -d su=16k,sw=160 /dev/mydevice

Hi John,

Thanks for reporting this issue. We are now working with our domain experts to correct the calculation for XFS. We have temporarily removed the calculation for XFS and will add it back as soon as we fix the problem.


We've corrected the calculation for XFS. Please try it.

The calculator should allow for spare disks to be part of the raidsets. This way a disk failure can be immediately overcome without having to wait for a acquisition/replacement window

Hi Subhendu,
Thanks sharing your idea. --spare-devices(-X) is an argument for creating RAID. This app is to create file systems on a given RAID. I do not see how spare diskcs can be specified when creating file systems. can you clarify?
In the notes for "Number of physical disks", we prompt users to not include hot spare disks.


True, this is just for filesystems, and spare disks are not relevant, but it would be really nice to have a similar tool to create/optimize the raidset when using mdraid to create the array.

An Advanced button option would be nice. We have an application that uses a set of filesystems like a pool before cutting an output. It was running out of "inodes" not disk space. We had to tweak our file system to use the maximum allowable inodes per filesystem. We guessed and went enormous so as not to fill the filesystem/Inode count. But a tool to better guest-amate that inode value based on filesystem size would have been useful.

Thanks Scott for reporting this. I've created an internal ticket to track it. We will evaluate it later.

Output of this tool is for raid level = 5, fs type =XFS, physical disks=10, raid chunk size =64 , bs=4096

mkfs.xfs -b 4096 -d su=64k,sw=9 /dev/mydevice

why is sw=9 and not 10

For RAID level 5, the effective data disks are (physical disks -1 ).

the help for the field number of disks is misleading "Number of physical disks
Specify the number of physical disks. Do not include hot spare disks - preparatory disk drives that are kept on active standby for use when a disk drive fails."

the help should be changed

there is no offering for Raid50

Is there an error with this web-page ? I don't see anything once I click on I'm using RHEL 7.5 with Firefox 60.1.0esr (64-bit)

Hi Strahil,

This page works well for me. Can you try again and let us know if it still does not work. Thanks, Dong

I tried yesterday and it worked.