Advice configuring ServeRAID 8k for performance
От | Kenneth Cox |
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Тема | Advice configuring ServeRAID 8k for performance |
Дата | |
Msg-id | op.vgy9k5ov5ru9c3@kent60.office.vivox.com обсуждение исходный текст |
Ответы |
Re: Advice configuring ServeRAID 8k for performance
Re: Advice configuring ServeRAID 8k for performance Re: Advice configuring ServeRAID 8k for performance Re: Advice configuring ServeRAID 8k for performance Re: Advice configuring ServeRAID 8k for performance Re: Advice configuring ServeRAID 8k for performance Re: Advice configuring ServeRAID 8k for performance |
Список | pgsql-performance |
I am using PostgreSQL 8.3.7 on a dedicated IBM 3660 with 24GB RAM running CentOS 5.4 x86_64. I have a ServeRAID 8k controller with 6 SATA 7500RPM disks in RAID 6, and for the OLAP workload it feels* slow. I have 6 more disks to add, and the RAID has to be rebuilt in any case, but first I would like to solicit general advice. I know that's little data to go on, and I believe in the scientific method, but in this case I don't have the time to make many iterations. My questions are simple, but in my reading I have not been able to find definitive answers: 1) Should I switch to RAID 10 for performance? I see things like "RAID 5 is bad for a DB" and "RAID 5 is slow with <= 6 drives" but I see little on RAID 6. RAID 6 was the original choice for more usable space with good redundancy. My current performance is 85MB/s write, 151 MB/s reads (using dd of 2xRAM per http://www.westnet.com/~gsmith/content/postgresql/pg-disktesting.htm). 2) Should I configure the ext3 file system with noatime and/or data=writeback or data=ordered? My controller has a battery, the logical drive has write cache enabled (write-back), and the physical devices have write cache disabled (write-through). 3) Do I just need to spend more time configuring postgresql? My non-default settings were largely generated by pgtune-0.9.3: max_locks_per_transaction = 128 # manual; avoiding "out of shared memory" default_statistics_target = 100 maintenance_work_mem = 1GB constraint_exclusion = on checkpoint_completion_target = 0.9 effective_cache_size = 16GB work_mem = 352MB wal_buffers = 32MB checkpoint_segments = 64 shared_buffers = 2316MB max_connections = 32 I am happy to take informed opinion. If you don't have the time to properly cite all your sources but have suggestions, please send them. Thanks in advance, Ken * I know "feels slow" is not scientific. What I mean is that any single query on a fact table, or any 'rm -rf' of a big directory sends disk utilization to 100% (measured with iostat -x 3).
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