Linux software RAID: RAID 5 vs RAID 10 performance and other RAID levels

Written by Gionatan Danti on . Posted in Linux & Unix

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Real word tests: PostgreSQL database

I run the same Sysbench test on PostgreSQL also. Please remind that this article don't want to compare the two database softwares: its target is to show how the RAID layout affect their performances. So, lets start with the prepare test:

PostgreSQL prepare benchmark

This time, RAID 5 is not much worse that RAID 10. The surprisingly thing, however, is to note how well the single disk setup copes with this task: it even outperform RAID 0. This is a completely unexpected thing and I need to conduct some additional tests to explain this behavior.

Now, its time for the one-million simple SQL query:

PostgreSQL simple benchmark

Now the standing are more or less in line with my expectations, with the exception of the RAID 5 results: while the simple Sysbench test is a read-only test, the results here are quite low. It can be related to the query planner's statistics update? Perhaps. Evidently, there is a reason why the PostgreSQL team explicitly discourage the use of RAID 5 with its database. Note that RAID 1 slightly outperform the single disk setup.

At last, we have the complex, read/write transactional test:

PostgreSQL complex benchmark

We have a similar picture here. RAID 5 is the slower, while RAID 0 and 10 are excellent performers. One more time, the RAID 1 setup is an hair above the single disk system.

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