Sorin Srbu wrote:
The guy who initially asked, IIRC, wanted some 3-4TB storage. This can be accomplished easily with a regular mid/maxi-size tower and a handful of 1TB-SATA drives. Even the midsize oldish Compucase-case I have at home can fit four 3,5"-drives in the hd-cage and another four in the 5,25"-bays. Suppose you fill that case with 1TB-drives and you have 8TB available. My argument is that there is no explicit need for the hardware you mention, despite how sexy it sounds. 8-)
Unfortunately it's common for most people that don't have experience with storage to confuse raw storage space with I/O performance(IOPS). It's not uncommon for someone to need say 4TB of space but need 50 or even 75 disks to use for that space because they need the IOPS. In my experience the average I/O size seems to be sub 20kB, which means a 10k RPM disk can only sustain about 1.9MBytes/second (15kB I/O size), before latency starts becoming a serious issue.
Of course if you have specialized applications you can probably push the I/O size much higher, I'm talking for just generic off the shelf type tasks, such as file serving, Oracle/MySQL databases, etc.
I came in late to the conversation I did see the original posts around wanting a cheap system and saw several good answers, I myself have used Openfiler and it's pretty good(for iSCSI, it seems flakey for NAS). Those types of systems really cannot be upgraded online safely. The poster I responded to asked about how do you upgrade, so I responded. The obvious answer for a "cheap" system is to upgrade the live box and reboot. There aren't many ways to upgrade such a system. Maybe if you have a cheap fiberchannel storage array(ala Infortrend) you can have two NAS front ends connected to the same back end storage, minimizing downtime and risk you can upgrade on system and flip people over to it, if it screws up you can flip back fairly quickly(though still not an online operation).
I recall a kernel update to Openfiler that caused random kernel panics. Fortunately I was able to go back to the earlier kernel. (this was running their "stable" distribution)
nate