# Linux - Rails - PostgreSQL partitioning **URL:** \ **Category:** Rails\ **Created:** [August 18, 2006, 4:21am UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430 "2006-08-18T04:21:50Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 18, 2006, 4:21am UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/1 "2006-08-18T04:21:50Z")
I am getting some larger hard drives and will migrate my intranet application onto the new hard drives. I am using CentOS 4. The current setup uses one small boot volume (ext2) and the rest is partitioned into one big LVM. Does it make sense to partition /var/lib/pgsql separately? (thinking mostly in terms of performance) Craig ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 18, 2006, 10:31am UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/2 "2006-08-18T10:31:55Z")
On 18/08/06, Craig W. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I am getting some larger hard drives and will migrate my intranet > application onto the new hard drives. I am using CentOS 4. The current > setup uses one small boot volume (ext2) and the rest is partitioned into > one big LVM. > > Does it make sense to partition /var/lib/pgsql separately? (thinking > mostly in terms of performance) If you’re using LVM, then probably not (you don’t have an easy way of telling where the extents are physically located on disk). ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 18, 2006, 3:08pm UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/3 "2006-08-18T15:08:26Z")
Dick D. wrote: > of telling where the extents are physically located on disk). > short answer: yes, I would explanation: It may not give you a big performance difference, but it does separate the postgres files from the rest of the system. If your main system drive does lots of updates, the fragmentation might slow things down. I don’t know the disk usage patterns of postgres, but I did have a separate partition for it and another app which did lots of updates and cause fragmentation. using a separate partition also insulates postgres from other daemons in case the fill up the disk. Jason E. ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 18, 2006, 5:35pm UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/4 "2006-08-18T17:35:49Z")
On Fri, 2006-08-18 at 09:06 -0400, Jason E. wrote: > > If you’re using LVM, then probably not (you don’t have an easy way > > I did have a separate partition for it and another app which did lots of > > updates and cause fragmentation. > > using a separate partition also insulates postgres from other daemons in > case the fill up the disk. * * * This server is only going to be used for the Rails intranet application. Thus the only things of interest are going to be Apache/PostgreSQL/ruby-rails and I will install enough to run a KDE desktop when necessary. I don’t think I will have any issues with fragmentation or rampant logging - at least thus far, the load level and disk usage has been tame but I do have a large section of code getting ready to be deployed which also means that the number of users simultaneously accessing the Rails application will jump up. Even with 10-15 simultaneous users, I don’t expect there to be too many issues with performance but I am trying to anticipate the issues and disk partitioning is much harder to do after the fact which is why I asked before I make my final deployment choices. Craig ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 19, 2006, 3:14pm UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/5 "2006-08-19T15:14:51Z")
Craig W. wrote: > > > > > > > > It may not give you a big performance difference, but it does separate > > * * * > > also means that the number of users simultaneously accessing the Rails > application will jump up. > > Even with 10-15 simultaneous users, I don’t expect there to be too many > issues with performance but I am trying to anticipate the issues and > disk partitioning is much harder to do after the fact which is why I > asked before I make my final deployment choices. If you have the option, leave say half or a quarter of your LVM volume group unallocated. Then you can create/grow volumes as needed. Jason ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 19, 2006, 5:35pm UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/6 "2006-08-19T17:35:00Z")
On Sat, 2006-08-19 at 10:03 -0400, Michael A. wrote: > PG partitioning can also provide performance benefits if used > your LVM on top of RAID10, you be fine for most applications. At that > point, you just need to benchmark your app and see if you are IO > bound. If so, rinse and repeat. * * * I was thinking primarily about partitioning to help out with IO. I am only going to use RAID 1 and keep the 3rd drive as a hot spare since what I have noticed is that RAID 5 doesn’t enhance performance on Linux - this is a Dell 1750 with a PERC 3/Di controller. I **might** be able to partition some of the databases down the road thinking that I will be able to archive and remove some of the data over time but I haven’t written that part of the application yet… 😉 Craig ---
**Author:** ![craigrails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@craigrails](https://www.ruby-forum.com/u/craigrails)\ **Post date:** [August 19, 2006, 4:04pm UTC](https://www.ruby-forum.com/t/linux-rails-postgresql-partitioning/65430/7 "2006-08-19T16:04:53Z")
> Does it make sense to partition /var/lib/pgsql separately? (thinking > mostly in terms of performance) Really depends on your usage pattern and you app. Partitioning with PG is great when you can logically partition your data, like by month or by division or something along those lines. You can then easily manage each partition individually, and say, only backup the most current month or archive the earliest month to disk and drop the partition. PG partitioning can also provide performance benefits if used correctly and you remember to turn on constraint\_exclusion. Then, you will hopefully only be searching/updating the tables that meet some sort of constraint criteria. So you need to see if you can easily logically partition your data and if you access patterns don’t usually cross too many partition boundaries. Oh, and pgpsql is a tremendous help in generating all the DDL that you might need. It sounds like you might also be talking about using partitioning to help out with IO. This really works best if you take a little more care in setting up your disks. If you follow best practices and put your LVM on top of RAID10, you be fine for most applications. At that point, you just need to benchmark your app and see if you are IO bound. If so, rinse and repeat.