●
Additional notes:
datasync
can significantly impact performance.
deferopens
deferopens
defers DVS client open requests to DVS servers for a given set
of conditions. When a file is open in stripe parallel mode or atomic stripe
parallel mode, DVS clients send the open request to a single DVS server only.
Additional open requests are sent as necessary when the DVS client performs
a read or write to a different server for the first time. The
deferopens
option
deviates from POSIX specifications. For example, if a file was removed after
the initial open succeeded but before deferred opens were initiated by a read
or write operation to a new server, the read or write operation would fail with
errno
set to
ENOENT
(because the open was unable to open the file).
nodeferopens
disables the deferral of DVS client open requests to DVS
servers. When a file is open in stripe parallel mode or atomic stripe parallel
mode, DVS clients send open requests to all DVS servers denoted by
nodename or nodefile.
●
Default setting:
nodeferopens
or
0
●
Associated environment variable:
●
Additional notes: none
distribute_create_ops
/
nodistribute_create_ops
distribute_create_ops
caused DVS to change its hashing algorithm so
that create and lookup requests are distributed across all of the servers, as
opposed to being distribute to a single server. This applies to creates, mkdirs,
lookups, mknods, links, and symlinks.
nodistribute_create_ops
is the default, and DVS uses its normal
algorithm of using just one target server.
●
Default setting:
nodistribute_create_ops
or
0
●
Associated environment variable: none
●
Additional notes: none
dwfs
/
nodwfs
dwfs
causes DVS to change its behavior to support a DataWarp file system.
nodwfs
is the default, where DVS does not support a DataWarp file system.
●
Default setting:
nodwfs
or
off
.
●
Associated environment variable: none
●
Additional notes: none
failover
/
nofailover
failover
enables failover and failback of DVS servers. If multiple DVS
servers are listed for a single DVS mount point and one or more of the servers
fails, operations for that mount point continue by using the subset of servers
still available. When the downed servers are rebooted and start DVS, any
client mount points that had performed failover operations failback to once
again include the servers as valid nodes for I/O forwarding operations.
nofailover
disables failover and failback of DVS servers. If one or more
servers for a given mount point fail, operations for that mount point behave as
Cray DVS
S3016
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