SSD Enabled For DreamHost Shared Hosting: Simple Performance Measurement

SSD is common for VPS and PaaS virtual machines for higher I/O performance. Now, it is coming to shared hosting too.

DreamHost states that "Now with solid state drives (SSDs), our standard web hosting loads pages 200% faster".

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.

Eric Ma

Eric is a systems guy. Eric is interested in building high-performance and scalable distributed systems and related technologies. The views or opinions expressed here are solely Eric's own and do not necessarily represent those of any third parties.

One comment:

  1. I got my touch on another server for shared hosting in DreamHost and run the `dd` test again. The results show higher write and read throughput on this server as follows.

    ericzma@situla:~$ 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, 6.95622 s, 77.2 MB/s
    ericzma@situla:~$ time mv testfile /dev/shm/
    
    real	0m4.190s
    user	0m0.016s
    sys	0m2.452s
    

    My guess is that this server is not as busy as the previous server I tested in the post.

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