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Lustre 1.6 Operations Manual

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How do I determine which <strong>Lustre</strong> server (MDS/OST) was connected to a<br />

particular storage device<br />

In instances when the hardware configuration has changed (e.g., moving<br />

equipment and re-connecting it), it is important to connect the right storage<br />

devices to the associated <strong>Lustre</strong> servers.<br />

<strong>Lustre</strong> writes a UUID to every OST and MDS. To view this information:<br />

1. Mount the storage device as ldiskfs<br />

mount -t ldiskfs /dev/foo /mnt/tmp<br />

2. Inspect the contents of the last_rcvd file in the root directory<br />

strings /mnt/tmp/last_rcvd<br />

The MDS/OST UUID is the first element in the last_rcvd file and is in a human<br />

readable form (e.g. mds1_UUID).<br />

3. Unmount the storage device and connect it to the appropriate <strong>Lustre</strong> server.<br />

umount /mnt/tmp<br />

Note – It is not possible to mismatch storage devices with their <strong>Lustre</strong> servers. If<br />

<strong>Lustre</strong> tries to mount such devices incorrectly, it would report a UUID mismatch to<br />

the syslog and refuse to mount.<br />

Does the mount option "--bind" allow mounting a <strong>Lustre</strong> filesystem to<br />

multiple directories on the same client system?<br />

Yes, this is supported. In fact, it is entirely handled by the VFS. No special<br />

filesystem support is required.<br />

Appendix D <strong>Lustre</strong> Knowledge Base D-33

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