Variable Name
Argument Type/Size
Purpose
passed through DVS to a remote
server.
6.1.3
DVS Client Mount Point Options
atomic
/
noatomic
atomic
enables atomic stripe parallel mode. This ensures that stripe parallel
requests adhere to POSIX read/write atomicity rules. DVS clients send each
I/O request to a single DVS server to ensure that the bytes are not interleaved
with other requests from DVS clients. The DVS server used to perform the
read, write, or metadata operation is selected using an internal hash involving
the underlying file or directory inode number and the offset of data into the file
relative to the DVS block size.
noatomic
disables atomic stripe parallel mode. If
nodename
or
nodefile
lists multiple DVS servers, and neither loadbalance nor cluster parallel mode
is specified, DVS stripes I/O requests across multiple servers and does not
necessarily adhere to POSIX read/write atomicity rules if file locking is not
used.
●
Default setting:
noatomic
or
0
●
Associated environment variable:
●
Additional notes: none
attrcache_timeout
attrcache_timeout
enables client-side attribute caching. File attributes
and
dentries
for
getattr
requests, pathname lookups, etc. are read from
DVS servers and cached on the DVS client for
n
seconds. Subsequent
lookups or
getattr
requests use the cached attributes until the timeout
expires, at which point they are read and cached again on first reference.
Attribute caching can significantly increase performance, most notably in
pathname lookup situations. When attribute caching is disabled, DVS clients
must send a lookup request to a DVS server for every level of a pathname,
and repeat this for every pathname operation. When it is enabled, it sends a
lookup request to a DVS server for every level of a pathname once per
n
seconds.
●
Default setting:
0
●
Associated environment variable: none
●
Additional notes: Not recommended for read-write files systems.
blksize=n
blksize=
n
sets the DVS block size to
n
bytes.
●
Default setting:
32768
●
Associated environment variable:
●
Additional notes:
blksize
is used in striping.
Cray DVS
S3016
143
