●
The third section contains fields for the smallest and largest request sizes (in bytes) for read and write
operations, and the number of successful and failed interprocess communication (IPC) requests, IPC
asynchronous requests, and IPC replies.
In addition, the
/proc/fs/dvs/ipc/stats
file displays DVS IPC statistics such as bytes transferred and
received, NAK counts, and so forth. It also displays message counts by type and size.
DVS statistics are enabled and collected by default.
●
To disable a DVS statistics file, write a zero into the file:
echo 0 > /proc/fs/dvs/stats
●
To re-enable a DVS statistics file, write a 1 into the file:
echo 1 > /proc/fs/dvs/stats
●
To reset the statistics values to zero, write a 2 into the file:
echo 2 > /proc/fs/dvs/stats
6.1.6.4 About DVS Client Requests
DVS provides a list of outstanding requests on client nodes in
/proc/fs/dvs/ipc/requests
, which lists the
DVS server node, the request, the DVS file system path,
uid
, time that the request has been waiting for a
response, and the associated
apid
. If the request is from a process that was not spawned through
aprun
, the
request
apid
is 0. An example output of the file looks like:
%
cat /proc/fs/dvs/ipc/requests
server: r0s1c1n3 request: RQ_LOOKUP path: /dsl/ufs/home user: 12795 time: 0.000 sec
apid: 3871
The file appears on DVS servers but returns an error when a user tries to access it.
6.1.7
Caveats
6.1.7.1 Caveat: Client Consistency
DVS supports close-to-open consistency, which means that files on client and server are consistent at
open()
and
close()
. However, while a file is open, DVS does not guarantee that the file on the client and the file on the
server are consistent.
6.1.7.2 Caveat: DVS blksize Must Match or be a Multiple of GPFS Block Size
When projecting a general parallel file system (GPFS), the client mount option
blksize
must match or be a
multiple of the GPFS blocksize. When projecting multiple GPFS file systems that have different block sizes, DVS
must have a different
/etc/fstab
entry for each file system.
In the case of two GPFS file systems, one with a 64 kilobyte (KB) block size, and another with a
1024KB block size, the
/etc/fstab
entries for DVS would look like the following:
/gpfs1 /dvs1 dvs path=/dvs1,nodefile=/etc/nidlist1,blksize=65536
/gpfs2 /dvs2 dvs path=/dvs2,nodefile=/etc/nidlist2,blksize=1048576
Cray DVS
S3016
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