[LU-2300] Wide striping leads to confusion for old clients

• Type: Improvement
• Resolution: Won't Fix
• Priority: Minor
• Assignee: WC Triage
• Reporter: Nathan Rutman

Description

1.8 client on 2.1 server:
> mkdir 161
> lfs setstripe -c 161 161
error: bad stripe count 161: Invalid argument (22)
error: setstripe: create stripe file '161' failed

Expectation #1: stripe count of "-1" gives a stripe width of 160 since that's all 1.8 can support. On large 1.8.x Lustre clusters -1 gives you 160 (without error, silent or otherwise) even if you have more OSTs.

Expectation #2: stripe count of "-1" gives a stripe width of "all OSTs", regardless of whether some clients can understand it.

Expectation #3: stripe count of "-1" gives a stripe count of 180 iff there are any clients < 2.1

Maybe we should have a MDS conf_param setting which is the "-1" stripe count value?