On Wed, Feb 3, 2010 at 10:05 PM, Ivan Voras <ivoras@xxxxxxxxxxx> wrote:
Can't do anything about this server now, but would surely keep in mind before upgrading other servers. Would you recommend the same speed drives(15K SAS) for RAID 1, or would a slower drive also work here (10K SAS or even SATA II)?
Yes, its running amd64 arch.
Thanks Ivan. That's a great explanation of the variables involved.
With regards
Amitabh Kant
On 02/03/10 16:10, Amitabh Kant wrote:If you really do have "heavy read and write" load on the server, nothing will save you from the bottleneck of having only 4 drives in the system (or more accurately: adding more memory will help reads but nothing helps writes except more drivers or faster (SSD) drives). If you can, add another 2 drives in RAID 1 and move+symlink the pg_xlog directory to the new array.
Hello
I have a server dedicated for Postgres with the following specs:
RAM 16GB, 146GB SAS (15K) x 4 - RAID 10 with BBU, Dual Xeon E5345 @
2.33GHz
OS: FreeBSD 8.0
Can't do anything about this server now, but would surely keep in mind before upgrading other servers. Would you recommend the same speed drives(15K SAS) for RAID 1, or would a slower drive also work here (10K SAS or even SATA II)?
maintenance_work_mem = 960MB # pg_generate_conf wizard 2010-02-03
checkpoint_completion_target = 0.9 # pg_generate_conf wizard 2010-02-03
effective_cache_size = 11GB # pg_generate_conf wizard 2010-02-03
work_mem = 160MB # pg_generate_conf wizard 2010-02-03
wal_buffers = 8MB # pg_generate_conf wizard 2010-02-03
checkpoint_segments = 16 # pg_generate_conf wizard 2010-02-03
shared_buffers = 3840MB # pg_generate_conf wizard 2010-02-03
max_connections = 100 # pg_generate_conf wizard 2010-02-03
Firstly, you need to run a 64-bit version ("amd64") of FreeBSD.I would appreciate if somebody could point out the sysctl/loader.conf
settings that I need to have in FreeBSD.
Yes, its running amd64 arch.
In /boot/loader.conf you will probably need to increase the number of sysv ipc semaphores:
kern.ipc.semmni=512
kern.ipc.semmns=1024
This depends mostly on the number of connections allowed to the server. The example values I gave above are more than enough but since this is a boot-only tunable it is expensive to modify later.
In /etc/sysctl.conf you will need to increase the shared memory sizes, e.g. for a 3900 MB shared_buffer:
kern.ipc.shmmax=4089446400
This is the maximum shared memory segment size, in bytes.
kern.ipc.shmall=1050000
This is the maximum amount of memory allowed to be used as sysv shared memory, in 4 kB pages.
If the database contains many objects (tables, indexes, etc.) you may need to increase the maximum number of open files and the amount of memory for the directory list cache:
kern.maxfiles=16384
vfs.ufs.dirhash_maxmem=4194304
If you estimate you will have large sequential reads on the database, you should increase read-ahead count:
vfs.read_max=32
Be sure that soft-updates is enabled on the file system you are using for data. Ignore all Linux-centric discussions about problems with journaling and write barriers :)
All settings in /etc/sysctl.conf can be changed at runtime (individually or by invoking "/etc/rc.d/sysctl restart"), settings in loader.conf are boot-time only.
Thanks Ivan. That's a great explanation of the variables involved.
With regards
Amitabh Kant
