Which filesystem are you on too? I've found that ext3 is significantly
faster than ext4 and xfs.
On 06/04/2010 04:01 PM, Stephen Thompson wrote:
>
> Thanks, yes it is Linux. I will look at those limits settings.
> And yes, I've built indexes and analyze (nothing to vacuum yet since
> it's a fresh import).
>
> Stephen
>
> On 06/04/2010 12:16 PM, Alan Brown wrote:
>
>> On Fri, 4 Jun 2010, Stephen Thompson wrote:
>>
>>
>>>
>>> Correction:
>>> I didn't notice the 8k per unit settings at first with postgres 8.1.
>>> Should read:
>>> effective_cache_size = 786432 # 6Gb
>>>
>> Assuming this is linux, you need to tweak /etc/sysctl/limits.conf a
>> little:
>>
>> postgres soft memlock unlimited
>> postgres hard memlock unlimited
>> @postgres hard memlock unlimited
>> @postgres soft memlock unlimited
>> bacula soft memlock unlimited
>> bacula hard memlock unlimited
>> @bacula soft memlock unlimited
>> @bacula hard memlock unlimited
>>
>> postgres soft rss unlimited
>> postgres hard rss unlimited
>>
>>
>> Don't forget to build the indexes and run analyse/vacuum commands.
>>
>> So far I'm finding Postgres is far more forgiving than MySQL and has far
>> fewer parts to tune...
>>
>>
>>
>>
>>>
>>> On 06/04/2010 10:58 AM, Stephen Thompson wrote:
>>>
>>>>
>>>> Hello everyone,
>>>>
>>>> We recently attempted a mysql to postgresql migration for our bacula
>>>> 5.0.2 server. The data migration itself was successful, however we are
>>>> disappointly either getting the same or significantly worse performance
>>>> out of the postgres db.
>>>>
>>>> I was hoping that someone might have some insight into this.
>>>>
>>>> Here is some background:
>>>>
>>>> software:
>>>> centos 5.5 (64bit)
>>>> bacula 5.0.2 (64bit)
>>>> postgresql 8.1.21 (64bit)
>>>> (previously... mysql-5.0.77 (64bit) MyISAM)
>>>>
>>>> database:
>>>> select count(*) from File --> 1,439,626,558
>>>> du -sk /var/lib/pgsql/data --> 346,236,136 /var/lib/pgsql/data
>>>>
>>>> hardware:
>>>> 1Tb EXT3 external fibre-RAID storage
>>>> 8Gb RAM
>>>> 2Gb SWAP
>>>> 2 dual-core [AMD Opteron(tm) Processor 2220] CPUs
>>>>
>>>>
>>>> Some of the postgres tuning that I've attempted thus far (comments are
>>>> either default or alternatively settings I've tried without effect):
>>>>
>>>> #shared_buffers = 1000 # min 16 or max_connections*2, 8KB each
>>>> shared_buffers = 262144 # 2Gb
>>>> #work_mem = 1024 # min 64, size in KB
>>>> work_mem = 524288 # 512Mb
>>>> #maintenance_work_mem = 16384 # min 1024, size in KB
>>>> maintenance_work_mem = 2097152 # 2Gb
>>>> #checkpoint_segments = 3 # in logfile segments, min 1, 16MB each
>>>> checkpoint_segments = 16
>>>> #checkpoint_warning = 30 # in seconds, 0 is off
>>>> checkpoint_warning = 16
>>>> #effective_cache_size = 1000 # typically 8KB each
>>>> #effective_cache_size = 262144 # 256Mb
>>>> effective_cache_size = 6291456 # 6Gb
>>>> #random_page_cost = 4 # units are one sequential page fetch cost
>>>> random_page_cost = 2
>>>>
>>>> Now, as to what I'm 'seeing'. Building restore trees are on par with my
>>>> previous mysql db, but what I'm seeing as significantly worse are:
>>>>
>>>> mysql postgresql
>>>> Within Bat:
>>>> 1) Version Browser (large sample job) 3min 9min
>>>> 2) Restore Tree (average sample job) 40sec 25sec
>>>> 3) Restore Tree (large sample job) 10min 8.5min
>>>> 2) Jobs Run (1000 Records) 10sec 2min
>>>>
>>>> Within psql/mysql:
>>>> 1) select count(*) from File; 1sec 30min
>>>>
>>>> Catalog dump:
>>>> 1) mysqldump/pgdump 2hrs 3hrs
>>>>
>>>>
>>>> I get a win on building Restore trees, but everywhere else, it's
>>>> painfully slow. It makes the bat utility virtually unusable as an
>>>> interface. Why the win (albeit moderate) in some cases but terrible
>>>> responses in others?
>>>>
>>>> I admit that I am not familiar with postgres at all, but I tried to walk
>>>> through some of the postgres tuning documents, including the notes in
>>>> the bacula manual to arrive at the above settings. Also note that I've
>>>> tried several variants on the configuration above (including the
>>>> postgres defaults), don't have a detailed play by play of the results,
>>>> but the time results above seemed typical regardless of what settings I
>>>> tweaked.
>>>>
>>>> Any help would be greatly appreciated!
>>>> Stephen
>>>>
>>>
>>>
>>>
>>
>
>
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