[LUDOC-49] MDT calculations don't include striping adjustments (Ch 5)

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Labels: QContent
• Business Value: 18
• Assignee: Richard Henwood (Inactive)
• Reporter: Richard Henwood (Inactive)

Description

The size of the MDT you need is proportional to the number of files you want to store and the number of stripes you anticipate using. Strips are not mentioned in the Manual in the section on calculating MTS size.

https://build.whamcloud.com/job/lustre-manual/lastSuccessfulBuild/artifact/lustre_manual.html#dbdoclet.50438256_87676

Cliff describes the situation thus:

[3:00:02 PM CDT] Richard Henwood: What is an approximate maximum number of files that I can have if my MDT is 450GB? The Manual says 2KB/inode which gives: 225 000 000. Does that sounds about right?
[3:19:46 PM CDT] Cliff White: inode size depends on stripe count. If no striping, afaik could be 512bytes/inode
[3:20:15 PM CDT] Cliff White: 2kb is somewhere arount 80 stripes, i think, ~4.5K is 160 stripes

Issue Links

• is related to: LUDOC-102 Put descriptions of "Inode size" and "Bytes per inode" in context for user (Ch 5)

Comments

[Linda Bebernes (Inactive)]

Changes merged

[Linda Bebernes (Inactive)]

Changes are ready for review at http://review.whamcloud.com/#/c/6847/

[Linda Bebernes (Inactive)]

Removed obsolete note from section 5.2.1:
Inode size depends on stripe count. Without any stripes an inode allocation of 512 bytes might be sufficient. As striping grows to ~80 stripes per file, the inode allocation is around 2KB. At 160 stripes, a rough estimate for inode allocation is 4.5KB

[Jodi Levi (Inactive)]

Richard to get more information on this request.