removing external usb hdd without unmounting causes reboot?

Don Lewis truckman at FreeBSD.org
Wed Jul 18 22:16:54 UTC 2007


On 18 Jul, Momchil Ivanov wrote:

> If the problem is in general with a file system, regardless of the provider, 
> then what does one do when a mounted smbfs becomes unavailable due to remote 
> host down, no route to host or some other network related problems? Same 
> question for NFS mounted filesystems?

In the case of NFS, nothing happens if the filesystem is idle.  If the
filesystem is active, any pending operations are retried indefinitely by
periodically resending the I/O requests if the file system is hard
mounted.  If the filesystem is soft mounted, then the I/O requests are
eventually timed out with the appropriate error status returned to the
process on the client.

An important difference between NFS and UFS is that a loss of network
connectivity (or a clean server reboot) can't cause any filesystem
inconsistencies in the NFS case because complex filesystem operations
that require multiple disk operations are treated as atomic operations
between the client and server.  For example, creating a new directory
requires a number of physical disk writes in the UFS case, and
unplugging the disk in the middle would result in an inconsistent
filesystem state.  In the NFS case, creating a new directory only
requires only one NFS operation over the wire, and the client is allowed
to keep retrying the operation until it receives a status response from
the server.  Retries might be necessary if either the request or the
response packet was dropped by the network, the server crashed, etc.



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