Lustre
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responsible to map the logical file offset for each I/O request to a specific OST
object and its object-local offset. In the RAID 0 pattern, files with multiple
objects are mapped in a round-robin fashion, and the size of each object is
approximately the total file size modulo the number of objects.
Typically the file layout does not change during the file’s lifetime. If this
is necessary (e.g., to change the number of stripes or migrate it to different
OSTs) the MDS can revoke the layout lock, which drops it from the clients’
cache. The client will refetch the new layout from the MDS with a DLM lock
request upon its next access.
In order to avoid a single point of contention during writes to a file with
multiple OST objects, the object size and