GPFS: Administration and Programming Reference - IRA Home

seconds to wait for those servers to come up. The decision to wait is controlled by the criteria managed
by the nsdServerWaitTimeWindowOnMount option.
Valid values are between 0 and 1200 seconds. The default is 300. A value of zero indicates that no
waiting is done. The interval for checking is 10 seconds. If nsdServerWaitTimeForMount is 0,
nsdServerWaitTimeWindowOnMount has no effect.
The mount thread waits when the daemon delays for safe recovery. The mount wait for NSD servers to
come up, which is covered by this option, occurs after expiration of the recovery wait allows the mount
thread to proceed.
nsdServerWaitTimeWindowOnMount
Specifies a window of time (in seconds) during which a mount can wait for NSD servers as described
for the nsdServerWaitTimeForMount option. The window begins when quorum is established (at
cluster startup or subsequently), or at the last known failure times of the NSD servers required to
perform the mount.
Valid values are between 1 and 1200 seconds. The default is 600. If nsdServerWaitTimeForMount is
0, nsdServerWaitTimeWindowOnMount has no effect.
When a node rejoins the cluster after having been removed for any reason, the node resets all the
failure time values that it knows about. Therefore, when a node rejoins the cluster it believes that the
NSD servers have not failed. From the node’s perspective, old failures are no longer relevant.
GPFS checks the cluster formation criteria first. If that check falls outside the window, GPFS then
checks for NSD server fail times being within the window.
pagepool
Changes the size of the cache on each node. The default value is 64 M. The minimum allowed value is
4 M. The maximum allowed value depends on amount of the available physical memory and your
operating system. Specify this value with the character M, for example, 60M.
prefetchThreads
Controls the maximum possible number of threads dedicated to prefetching data for files that are read
sequentially, or to handle sequential write-behind.
The actual degree of parallelism for prefetching is determined dynamically in the GPFS daemon. The
minimum value is 2. The maximum value is 104. The default value is 72. The maximum value of
prefetchThreads plus worker1Threads is:
v On 32-bit kernels, 164
v On 64-bit kernels, 550
subnets
Specifies subnets used to communicate between nodes in a GPFS cluster.
mmchconfig Command
Enclose the subnets in quotes and separate them by spaces. The order in which they are specified
determines the order that GPFS uses these subnets to establish connections to the nodes within the
cluster. For example, subnets=″192.168.2.0″ refer to IP addresses 192.168.2.0 through 192.168.2.255
inclusive.
An optional list of cluster names may also be specified, separated by commas. The names may contain
wild cards similar to those accepted by shell commands. If specified, these names override the list of
private IP addresses. For example, subnets=″10.10.10.0/remote.cluster;192.168.2.0".
This feature cannot be used to establish fault tolerance or automatic failover. If the interface
corresponding to an IP address in the list is down, GPFS does not use the next one on the list. For
more information about subnets, see General Parallel File System: Advanced Administration Guide and
search on Using remote access with public and private IP addresses.
tiebreakerDisks
Controls whether GPFS will use the node quorum with tiebreaker algorithm in place of the regular node
based quorum algorithm. See General Parallel File System: Concepts, Planning, and Installation Guide
Chapter 8. GPFS commands 91