RAID vs SSD vs FusionIOVadim Tkachenko
In benchmarks passion (see my two previous posts) I managed to setup all three devices (RAID was on board; Intel X25-E SSD connected to HighPoint controller, FusionIO card) on our working horse Dell PowerEdge R900 (btw, to do that I had to switch from CentOS 5.2 to Ubuntu 8.10, as CentOS was not able to start with attached SSD card to HighPoint controller) and along with other tests I ran tpcc-like IO-bound workload on all devices.
For tests I used MySQL 5.4/InnoDB, and all other parameters are the same from previous posts (100W, buffer_pool 3GB). Filesystem – XFS mounted with nobarrier option.
Graphical results are here
and average results:
RAID10 – 7439.850 TPM
SSD – 10681.050 TPM
FusionIO – 17372.250 TPM
However what should be noted – both SSD and FusionIO are run in “non-durable” mode, that is you may lose some transactions in case of power outage (see my post https://www.percona.com/blog/2009/03/02/ssd-xfs-lvm-fsync-write-cache-barrier-and-lost-transactions/).
While results for SSD (note it is single device, in comparison to RAID 10 on 8 disks) and FusionIO are impressive, it is worth to consider price/performance parameter.
Here is my very rough calculation:
For RAID 10 we use 8 73GB SAS 2.5″ 15K RPM disks, with price 190$ per disks it gives us 1520$ for 292GB useful space, or ~ 5.2$ per GB.
For SSD I can get 32GB card for 390$, which is ~12.1$ per GB
For FusionIO I really not sure what is price (it was given as only for tests), but quick googling gave me 30$ per GB, so for 160GB card gives 4800$.
Now simple dividing TPM on price of IO system, we have
RAID 10 – 4.8 TPM / $
SSD – 27 TPM / $
FusionIO – 3.6 TPM / $
Please note that price of transaction is not the main criteria to consider, as total TCO for systems with SSD may be much cheaper (considering you need less servers, less space, less power). Also worth to consider that SSD is only 32GB space and to have the same space as FusionIO we need 4 cards (but it still will be cheaper than FusionIO), but it also may improve performance as such setup will be able to handle IO requests in parallel.