He estado leyendo sobre la configuracion de postgresql, pero tengo un
servidor que no me da el rendimiento que deveria de dar, lo monitoreo con
top, ps y pg_stat_activity y para lo que esta haciendo no deberia de ponerse
tan lento a como se pone, las tablas estan bien indexadas y se realizan
vacuum regularmente.
Las caracteristicas del servidor son:
4 Procesadores Intel Xeon Duales de 3.0Ghz
12 GB de Memoria RAM
El sistema esta operativo esta en 2 discos en RAID 1
La base de datos esta en 4 discos en RAID 5
Es un servidor dell (No recuerdo el modelo lo administro remotamente)
S.O Slackware 11.0 Linux 2.6.17.7
A alcanzado 2000 conexiones simultaneas al postgresql en max_connections le
puse 3000 para que sobrara un poco para procesos nuevos.
Tube que dividir la carga con otro servidor para que trabajara mejor y si
pues a fuerza mejoro pero por que se ahora solo alcanza a tener 500
conexiones simultaneas, pero aun asi lo sigo viendo con mucha carga.
Mi duda es mas que nada sobre la configuracion de memoria que deberia de
tener en shared_buffers y effective_cache_size.
Su ayuda se los agradeceria mucho.
En alguna pagina de internet encontre esto:
Tuning PostgreSQL for performance
2 Some basic parameters
2.1 Shared buffers
# Start at 4MB (512) for a workstation
# Medium size data set and 256-512MB available RAM: 16-32MB (2048-4096)
# Large dataset and lots of available RAM (1-4GB): 64-256MB (8192-32768)
Entonces si yo tengo 12GB de RAM es correcto que use en shared_buffers =
98304??
tambien he leido que aumentar mucho la shared_buffers alenta los procesos,
le puse 81920 se hacerca a lo correcto?? (lo multiplique por 10)
Estas son algunas seciones de configuracion del archivo postgresql.conf
#---------------------------------------------------------------------------
# FILE LOCATIONS
#---------------------------------------------------------------------------
# The default values of these variables are driven from the -D command line
# switch or PGDATA environment variable, represented here as ConfigDir.
#data_directory = 'ConfigDir' # use data in another directory
#hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file
#ident_file = 'ConfigDir/pg_ident.conf' # IDENT configuration file
# If external_pid_file is not explicitly set, no extra pid file is written.
#external_pid_file = '(none)' # write an extra pid file
#---------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#---------------------------------------------------------------------------
# - Connection Settings -
listen_addresses = '*' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost', '*' = all
port = 5432
max_connections = 3000
# note: increasing max_connections costs ~400 bytes of shared memory per
# connection slot, plus lock space (see max_locks_per_transaction). You
# might also need to raise shared_buffers to support more connections.
#superuser_reserved_connections = 2
#unix_socket_directory = ''
#unix_socket_group = ''
#unix_socket_permissions = 0777 # octal
#bonjour_name = '' # defaults to the computer name
#---------------------------------------------------------------------------
# RESOURCE USAGE (except WAL)
#---------------------------------------------------------------------------
# - Memory -
shared_buffers = 81920 # min 16 or max_connections*2, 8KB each
temp_buffers = 5000 # min 100, 8KB each
max_prepared_transactions = 1000 # can be 0 or more
# note: increasing max_prepared_transactions costs ~600 bytes of shared
memory
# per transaction slot, plus lock space (see max_locks_per_transaction).
work_mem = 10240 # min 64, size in KB
maintenance_work_mem = 253952 # min 1024, size in KB
max_stack_depth = 4096 # min 100, size in KB
# - Free Space Map -
#max_fsm_pages = 20000 # min max_fsm_relations*16, 6 bytes each
#max_fsm_relations = 1000 # min 100, ~70 bytes each
# - Kernel Resource Usage -
#max_files_per_process = 1000 # min 25
#preload_libraries = ''
# - Cost-Based Vacuum Delay -
#vacuum_cost_delay = 0 # 0-1000 milliseconds
#vacuum_cost_page_hit = 1 # 0-10000 credits
#vacuum_cost_page_miss = 10 # 0-10000 credits
#vacuum_cost_page_dirty = 20 # 0-10000 credits
#vacuum_cost_limit = 200 # 0-10000 credits
# - Background writer -
#bgwriter_delay = 200 # 10-10000 milliseconds between rounds
#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned/round
#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written/round
#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned/round
#bgwriter_all_maxpages = 5 # 0-1000 buffers max written/round
#---------------------------------------------------------------------------
# WRITE AHEAD LOG
#---------------------------------------------------------------------------
# - Settings -
#fsync = on # turns forced synchronization on or off
#wal_sync_method = fsync # the default is the first option
# supported by the operating system:
# open_datasync
# fdatasync
# fsync
# fsync_writethrough
# open_sync
#full_page_writes = on # recover from partial page writes
#wal_buffers = 8 # min 4, 8KB each
#commit_delay = 0 # range 0-100000, in microseconds
#commit_siblings = 5 # range 1-1000
# - Checkpoints -
checkpoint_segments = 20 # in logfile segments, min 1, 16MB each
#checkpoint_timeout = 300 # range 30-3600, in seconds
#checkpoint_warning = 30 # in seconds, 0 is off
# - Archiving -
#archive_command = '' # command to use to archive a logfile
# segment
#---------------------------------------------------------------------------
# QUERY TUNING
#---------------------------------------------------------------------------
# - Planner Method Configuration -
#enable_bitmapscan = on
#enable_hashagg = on
#enable_hashjoin = on
#enable_indexscan = on
#enable_mergejoin = on
enable_nestloop = off
enable_seqscan = off
#enable_sort = on
#enable_tidscan = on
# - Planner Cost Constants -
effective_cache_size = 65536 # typically 8KB each
#random_page_cost = 4 # units are one sequential page fetch
# cost
#cpu_tuple_cost = 0.01 # (same)
#cpu_index_tuple_cost = 0.001 # (same)
#cpu_operator_cost = 0.0025 # (same)
El sysctl.conf
contiene lo siguiente:
kernel.shmmax = 970170573
kernel.shmall = 970170573
kernel.sem = 400 42000 32 1024
vm.overcommit_memory = 2
Es correcta la configuracion que tengo?
Alguna sugerencia?
Gracias de antemano....
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