No, an upgrade should not cause any downtime. However, on the first startup -
since MinIO will attempt to migrate any existing IAM data - the boot process may
take slightly longer, but may not be visibly noticeable. Once the migration has

		if pinfo.Err == nil {
			// found a pool
			return pinfo, z.poolsWithObject(poolObjInfos, opts), nil
		}

		if isErrReadQuorum(pinfo.Err) && !opts.MetadataChg {
			// read quorum is returned when the object is visibly
			// present but its unreadable, we simply ask the writes to
			// schedule to this pool instead. If there is no quorum
			// it will fail anyways, however if there is quorum available