On DVS clients, specifies the number of seconds between checks for dirty files
that need to request the last sync time from the server.
This parameter is part of the periodic sync feature.
●
Default value: 300 (server), 600 (client)
●
To view read-only:
cat
/sys/module/dvs/parameters/sync_period_secs
●
To change prior to boot, add these lines to
<nid_of_choice>
/etc/modprobe.d/dvs-local.conf
:
# Set the sync period (seconds) on DVS server/client
options dvs sync_period_secs=300
●
To change dynamically:
hostname#
echo 300 > /proc/fs/dvs/sync_period_secs
6.1.8.6 About the Quiesce DVS-projected File System
Sites can use the DVS quiesce capability to temporarily suspend traffic to a DVS-projected file system on any
number of DVS servers. When a directory is quiesced, the DVS server completes any outstanding requests but
does not honor any new requests for that directory. Any outstanding requests for that directory are displayed
in
/proc/fs/dvs/quiesce
file system interface. Administrators can read that proc file to know when it is safe
to perform operations on the quiesced directory without any possibility of interference by a DVS client. DVS
quiesce can be used when a file system needs to be repaired or to safely take a DVS server node out of service.
CAUTION: Because it may cause data corruption, do not use DVS quiesce to:
●
quiesce a directory that is being used by DataWarp
●
quiesce a directory on every DVS server
To use DVS quiesce, an administrator writes into and reads from
/proc/fs/dvs/quiesce
.
How Quiesce Works: the Userspace Application View
Userspace applications have no visibility into any specific quiesce information. A quiesced directory will present in
one of two ways:
●
Entirely normally, if the directory is quiesced only on servers that the application is not using.
●
Useable but with degraded performance, if the application finds that its main server is quiesced and must
query other servers.
How Quiesce Works: the Server View
To provide the quiesce capability, DVS servers keep a list of quiesced directories and the current outstanding
requests on each quiesced directory. When an admin requests that DVS quiesce a directory on a server, DVS
does the following:
●
adds that directory to the server's list of quiesced directories
●
iterates over all open files, closing any file that resides in the quiesced directory and setting a flag to indicate
that the file was closed due to the directory being quiesced
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