Olá, Marcio.
Nunca passei por isso e encontrei poucas referências de seu problema na internet. Nestas, os usuários relatam o problema no bond mas não o reboot do host.
Alguns falam de valor do MTU e em que tipo de PIF é adicionado 9000, o tipo de bond, porém, não vi ninguém chegando a uma conclusão.
http://discussions.citrix.com/topic/355726-bond-status/
Fui atrás das updates que ainda faltam pra você aplicar e encontrei informações relevantes:
Hotfix XS62E004
This hotfix resolves the following issues:
1. Certain network traffic patterns can cause kernel memory leak in the Control Domain (dom0), which can eventually result in a XenServer host crash.
2. Path failures in high-speed storage networks, combined with a very fast CPU, may lead to premature I/O errors.
3. In some cases, it may not be possible to automatically recover storage paths from outages in multipathed environments.
Hotfix XS62E005
This hotfix resolves the following issues:
7. When using Jumbo Frames for storage traffic (with an MTU larger than 1500 on the storage interface), attempts to reboot a host with High Availability (HA) enabled may lead to the XenServer host being unable to fully boot.
Hotfix XS62E011
This hotfix resolves the following issues:
1. In some cases, Multipathing is shown as €˜'Not active'€™ in XenCenter even when there are active paths present in the corresponding storage repository (SR).
2. LVM-based SRs (for example, LVMoHBA, LVMoiSCSI, and LVM) incorrectly allow customers to create VHD files that are up to 2048 GB in size, and file-based SRs (for example, NFS and EXT) allow customers to resize VHD files that are up to 2048 GB in size. However, writing more than 2043 GB of data to the virtual disk images (VDIs) can lead to a VDI corruption. Installing this hotfix ensures VMs with VDIs larger than 2043GB get I/O errors when attempting to write more than 2043GB of data.
3. A mismatch in protocol between the Storage plugin and XenCenter can stop users from creating an iSCSI-based SR when specifying more than one target IP address.
Sei que isso pode não ser a causa de seu problema, mas, recomendo trabalhar com ambiente sempre atualizado, até para em um troubleshooting se descartar questões de "falta de updates".
Aplique as atualizações restantes. Elas podem resolver seu problema. Caso contrário, poste o resultado e tentarei te guiar por alguma solução.
Abraços!
Links para os hotfixes: