SSD is common for VPS and PaaS virtual machines for higher I/O performance. Now, it is coming to shared hosting too.
We ourselves are happy to know this performance improvement with the price kept the same. Good work, DreamHost.
Simple I/O performance measurement on DreamHost shared hosting account
To see how does the new SSD-based storage performs, we did simple tests in one account on one server of DreamHost’s shared hosting. The test is simple: moving files from the home (mounted XFS filesystem which stores the site content) and
/dev/shm/ which is a in-memory file system or using
dd go generate files. The results will reflect how the reads and write perform.
Note that we do not have the root access to flush buffers and invalidate caches, and there are many concurrent users. Hence, the server should be considered relatively busy, and the result here should only be viewed as a general "feeling" of the performance.
Moving small files
The commands and results are shown as follows.
test@seginus:~$ ls -lha 49MBfile.pdf -rwxr-xr-x 1 test pg000000 49M Mar 5 23:23 49MBfile.pdf test@seginus:~$ time mv ./49MBfile.pdf /dev/shm/ real 0m0.602s user 0m0.012s sys 0m0.176s test@seginus:~$ time mv /dev/shm/49MBfile.pdf ./ real 0m0.307s user 0m0.008s sys 0m0.216s test@seginus:~$ time mv ./49MBfile.pdf /dev/shm/ real 0m0.291s user 0m0.016s sys 0m0.172s test@seginus:~$ time mv /dev/shm/49MBfile.pdf ./ real 0m0.225s user 0m0.000s sys 0m0.208s test@seginus:~$ time mv ./49MBfile.pdf /dev/shm/ real 0m0.331s user 0m0.000s sys 0m0.188s test@seginus:~$ time mv /dev/shm/49MBfile.pdf ./ real 0m0.262s user 0m0.000s sys 0m0.216s
If we consider the largest 0.602s as the worst time for accessing the 49MB file, the throughput is still around 81.4 MB/s.
dd and moving large files
The commands and results are as follows.
test@seginus:~$ dd if=/dev/zero of=./testfile bs=512M count=1 oflag=direct 1+0 records in 1+0 records out 536870912 bytes (537 MB) copied, 9.26255 s, 58.0 MB/s test@seginus:~$ time mv testfile /dev/shm/ real 0m4.802s user 0m0.052s sys 0m2.148s
The write and read throughput are 58.0 MB/s and 106.6 MB/s.
Although these numbers may not represent the exact actual I/O throughput for your site as the server may be busier or freer depending on the load, these results do reflect that the performance is good regarding the low price of the shared hosting plan.