Hopefully you’ve noticed some drastic improvements in load times, as I’ve moved Gyrate Dot Org to new hardware. My old “server” was a little Mini-ITX box with a 1Ghz VIA Nehemiah CPU, 256MB of memory, and a laptop hard drive. It certainly was quiet and power efficient, but it was frustratingly slow sometimes. The new server is actually my old desktop with an AMD Athlon XP 2500+ CPU, 512MB of memory, and two brand new 750GB WD Caviars running in a RAID 1 array (yes, these drives are dead silent like the reviews say). I decided to go with Linux software raid after reading some interesting opinions on Linux Software RAID vs Hardware RAID. I also found some surprising benchmarks showing that Linux software RAID is actually faster than a lot of consumer-level SATA RAID cards.
Compared to the old hardware…
root@old-server:~# hdparm -Tt /dev/hda /dev/hda: Timing cached reads: 278 MB in 2.01 seconds = 138.26 MB/sec Timing buffered disk reads: 88 MB in 3.00 seconds = 29.32 MB/sec
the new hardware shows huge improvements in disk transfer rates, pretty much in line with what I expected.
root@new-server:~# hdparm -tT /dev/md0 /dev/md0: Timing cached reads: 950 MB in 2.00 seconds = 474.49 MB/sec Timing buffered disk reads: 222 MB in 3.01 seconds = 73.81 MB/sec
With twice as much memory as before, I’m also not swapping nearly as much (or really at all for that matter). But what I didn’t expect was for Linux software RAID and LVM2 to have such a big impact on my load average. It actually seems to be around 10-20% higher on average, even with a much faster CPU. Interesting…
2 Comments
raid1 gets to cheat and stripe reads. compare a write test if you want to see the difference in drives, even though it’s probably not going to be written to very often…
thats true, but i get the same results even when i run a read test against the individual drives. i wonder why that is…