Yet another interesting observation…
Now this is interesting. If you have been following my quest for a perfect self-assembled NAS box, you would have read about the initial performance statistics. I am not trying to be 100% scientific, but provided observation that I have seen.
My main pool of storage is on 6 1TB WD Green Drive. 2 of them are on the Atom 330 MB with Intel 945G’s built-in SATA port and 4 on the Sil3124 add-on card. The 6 disks are formatted into a RAIDZ volume. Performance number is around 14MB/s write and 6.5MB/s read. The writing, while averaging 14MB/s, fluctuate a lot. I wasn’t sure if it was due to the CPU, Interface or network interface.
I also have another Sil4726 storage box that has 5 WD 1TB Green drive that I have hook up to the NAS via a USB2 to eSATA converter. The 5 drives has also been formatted as a RAIDZ volume. Because it is on USB2, I was not as keen on using it as the main storage pool. However, I just found some old drives with older data archive that I decided to move to this storage volume.
To my surprise, this pool of storage is able to substain a 14MB/s write with almost no fluctuation in speed (again, i am just looking at the number reported by Teracopy).
I have 2 theory on this observation:
1) Atom 330′s max performance for RAIDZ is maybe around 14MB/s on OpenSolaris.
2) It was a surprise to me that the USB2 pool is actually able to sustained that kind of write speed, which is faster than through native SATA. Therefore, I think that the PCI interface card is too limiting in the bandwidth that the write speed actually fluctuate so much. The USB2 interface, while technically inferior in speed, was linked more closely to the southbridge that it is actually faster. You probably will get better performane with a higher end PCI Express add-on card if you build a NAS on a more powerful MB.
Upgrading or not to snv_118
The thing about any system that you have put too much data on is the stability of it. While I haven’t seen any major issue with snv_117 and have been fairly happy with it for sometime, OpenSolaris has just been upgraded to snv_118.
For OpenSolaris, upgrading an OS is actually a fairly safe operation… even without any preparation. If you have to upgrade Windows Vista from SP1 to SP2. The only safe way to do it is to take a image dump of the partition with programs like Norton Ghost or Clonezilla and the like. Upgrade the OS and if anything bad happens, rollback to the previous version using the image.
OpenSolaris, if you take advantage of using ZFS as the root filesystem, the update manager actually takes a ZFS snapshot of the OS, then install the new version of the OS on. At boot, you can easily choose to boot to a previous version that was snapshotted (is there such a word)…. no fuss no hassle…
Even with that in mind, it is still a scary thought to upgrade… Let me think about it a bit more…
Have been away for about a month on various vacation break… During this time, my OpenSolaris NAS box (I called the server Falcon), has been rock stable. I am using it daily and had not need to reboot it for more than a month.
I have received a few comments asking for some performance number. Purely based on my own observation and memory, I have seen an average of about 12-14MB/s for writing over Gigabit Ethernet. However, the speed of writing varies a lot, anywhere from 2-3MB/s to 15MB/s. I get this stats from Teracopy’s calculation… so I can’t tell you for sure if it is totally accurate. Considering that the same machine writing to a USB2 hard drive (WDC Essential 1TB) would score about 17MB/s, I think this is a pretty good speed for a 6 disk RAIDZ pool using Atom 330.
The strange thing is that reading is only about 6.5MB/s. It hasn’t been much of a problem for me since I store a lot of media on that NAS pool for viewing on various machines that I have around the house. However, since I haven’t done any HD streaming, I am not sure if this is going to be an eliminating factor or not.
My feeling is that Atom 330 is underpowered. However, it depends on what your main objective is. My main objective is to have a low power NAS device for storing all my media, Atom 330 serves this purpose well.
