xsan client stopped mounting raid

Good Morning Community, I have xsan 2.2 and os 10.7.5

two of my clients stopped mounting the raid. they authenticate to the mdc but will not mount. erro on client says check fiber connections. i have switched computer with working connection and problem follows machine. xsan is working with all other machines only two. MDC system log shows

error mounting volume...operation coundn't be completed (SANTractionErrorDomain error 100007.) (100007)

any ideas? All help is greatly appreciated

thank you