Difference between revisions of "DPM Glossary"
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===DPM Machines=== | ===DPM Machines=== | ||
| − | * '''DPM Head Node''': The machine hosting [[SRM]] daemons for [[Disk Pool Manager|DPM]]. For a typical [[DPM Yaim Install]] this machine also hosts the DPM (pool manager) and DPNS (name server) daemons and | + | * '''DPM Head Node''': The machine hosting [[SRM]] daemons for [[Disk Pool Manager|DPM]]. For a typical [[DPM Yaim Install]] this machine also hosts the DPM (pool manager) and DPNS (name server) daemons and (MySQL) databases; but this is not strictly necessary - DPM can have these daemons hosted elsewhere (and even have the backend database server for these daemons on a different machine again). As of DPM 1.9.x, DPM can also operate using its future DOME mechanism, which obsoletes the DPM and DPNS daemons in favour of a lighter-weight infrastructure. |
* '''DPM Disk Server''': A machine hosting filesystems which form part of a DPM Pool. | * '''DPM Disk Server''': A machine hosting filesystems which form part of a DPM Pool. | ||
===DPM Concepts=== | ===DPM Concepts=== | ||
| − | * '''Filesystem''': A single POSIX filesystem hosted on a DPM machine which forms part of a DPM Pool. The most important property which can be set on a filesystem is ''status'', in particular filesystems can be marked <tt>RDONLY</tt> which will prevent any incoming files from being written to this filesystem. | + | * '''Filesystem''': A single (usually POSIX) filesystem hosted on a DPM machine which forms part of a DPM Pool. The most important property which can be set on a filesystem is ''status'', in particular filesystems can be marked <tt>RDONLY</tt> which will prevent any incoming files from being written to this filesystem, or <tt>DISABLED</tt>, which prevents any accesses at all. |
| − | * '''Pool''': An aggregation of filesystems to form a logical entity inside DPM. Many properties can be set at the pool level: default SRM storage class (volatile, durable), default file size, filesystem selection algorithm, reservation for a particular VO. | + | |
| + | * '''Pool''': An aggregation of filesystems to form a logical entity inside DPM. Many properties can be set at the pool level: default SRM storage class (volatile, durable), default file size, filesystem selection algorithm, reservation for a particular VO. Files written to a pool are distributed (at the file level) across all filesystems in the pool, via a weighting mechanism (by default, equally for each filesystem). | ||
===Example=== | ===Example=== | ||
Latest revision as of 15:03, 3 May 2017
DPM Machines
- DPM Head Node: The machine hosting SRM daemons for DPM. For a typical DPM Yaim Install this machine also hosts the DPM (pool manager) and DPNS (name server) daemons and (MySQL) databases; but this is not strictly necessary - DPM can have these daemons hosted elsewhere (and even have the backend database server for these daemons on a different machine again). As of DPM 1.9.x, DPM can also operate using its future DOME mechanism, which obsoletes the DPM and DPNS daemons in favour of a lighter-weight infrastructure.
- DPM Disk Server: A machine hosting filesystems which form part of a DPM Pool.
DPM Concepts
- Filesystem: A single (usually POSIX) filesystem hosted on a DPM machine which forms part of a DPM Pool. The most important property which can be set on a filesystem is status, in particular filesystems can be marked RDONLY which will prevent any incoming files from being written to this filesystem, or DISABLED, which prevents any accesses at all.
- Pool: An aggregation of filesystems to form a logical entity inside DPM. Many properties can be set at the pool level: default SRM storage class (volatile, durable), default file size, filesystem selection algorithm, reservation for a particular VO. Files written to a pool are distributed (at the file level) across all filesystems in the pool, via a weighting mechanism (by default, equally for each filesystem).
Example
root of se2-gla:~# dpm-qryconf
POOL srmStore DEFSIZE 1024.00M GC_START_THRESH 0 GC_STOP_THRESH 0 DEFPINTIME 100000 PUT_RETENP 86400 FSS_POLICY maxfreespace GC_POLICY lru RS_POLICY fifo GID 0 S_TYPE -
CAPACITY 2.63T FREE 2.32T ( 88.4%)
pool1-gla.scotgrid.ac.uk /gridstorage/c1 CAPACITY 538.04G FREE 452.35G ( 84.1%)
pool1-gla.scotgrid.ac.uk /gridstorage/d1 CAPACITY 538.04G FREE 454.27G ( 84.4%) RDONLY
pool1-gla.scotgrid.ac.uk /gridstorage/e1 CAPACITY 538.04G FREE 455.26G ( 84.6%) RDONLY
pool1-gla.scotgrid.ac.uk /gridstorage/f1 CAPACITY 538.04G FREE 453.32G ( 84.3%) RDONLY
pool1-gla.scotgrid.ac.uk /gridstorage/g1 CAPACITY 538.04G FREE 451.75G ( 84.0%)
pool2-gla.scotgrid.ac.uk /gridstorage/sdc1 CAPACITY 1.58T FREE 1.44T ( 91.4%)
POOL testPool DEFSIZE 0 GC_START_THRESH 0 GC_STOP_THRESH 0 DEFPINTIME 0 PUT_RETENP 86400 FSS_POLICY maxfreespace GC_POLICY lru RS_POLICY fifo GID 2010 S_TYPE -
CAPACITY 0 FREE 0 ( 0.0%)
se2-gla.scotgrid.ac.uk /gridstorage CAPACITY 168.53G FREE 149.45G ( 88.7%) RDONLY
In this case, se2-gla is the DPM Head Node. pool1-gla and pool2-gla are DPM disk servers. The whole DPM consists of two pools, srmStore, which has 6 filesystems, and testPool, which has only 1. A number of the filesystems are currently marked read only, and note that testPool is reserved for a specific group (in this case dteam).
