Gnome, thanks for the info.
np
Knowing that a bad drive can be replaced with any similar or larger drive is one point for FreeNAS. I was working on the worst case scenario, that a drive had to be replaced with an identical drive - same model, same size, same firmware, same speed, etc. What about replacing a 7200 drive with a 5900, or a vari speed?
ZFS doesn't care about the drive apart from the fact that the size must be equal or more to replace a current disk. Things like speed, type (PATA vs SATA), model, etc. isn't even known to ZFS.
The sector size does play a role, but FreeNAS has the "force 4KB sector size option" when you create the array. I suggest you check that option even if you don't know if your drives are 4KB sector size drives or what it is.
Btw. the 4KB sector size is applicable to ANY NAS, it has to do with the disks and how they are accessed. There is now way around it, no hackity hack to make it go away. Western Digital refer to this as Advanced Format. Seagate I think has another name. Either way, all new drives are now 4KB sector size.
I actually wonder what Drobo does about 4KB sector size because if you don't format correctly, it places a lot of extra wear on your disk and the performance of the disk is pathetic (4mb/s vs 150mb/s).
Well you can upgrade your FreeNAS box by adding an extra RAID card (eg. IBM M1015 flashed to LSI 9112 IT mode gives you extra 8 SATA ports, costs ~R1k on eBay). Then you can add extra disks. But you cannot "upgrade" by increasing the space of an existing RAID-Z or ZFS Mirror.The upgrading question is (for me) easily summed up - you can't upgrade a FreeNAS box. Buy a new one, copy everything across, and get rid of the old one. At least I know now.
It's now just a case of whether I'm happy to live with the restrictions, costs and benefits of the different options. Right now a mirrored 3TB drive for my desktop will cost about R 3300. A 6TB (12TB raw) FreeNAS upgrade for my MicroServer is about R 7800, and I get a static, but fast and reliable system (do I need a caching SSD?). A Drobo is about R 11700 for 6TB (12TB raw), or R 13400 for 9TB (15TB raw).
You don't need a caching SSD. With my NAS (Intel 2100T CPU, Intel 1GB NIC) I get 100-110megabytes/s copy speed (100% of the time). I have 6x2TB Seagate 5400RPM + 3x2TB Western Digital GP drives all in a single RAID-z1. I've had 2 disk failures thus far, both when I bought new drives. Both times recovery was as easy as falling out of a tree.
In fact the second time a hard-drive failed, I also had bad sectors on another drive. ZFS reported to me that there were 3 files which are probably damaged because there were multiple failures. Those files still play fine tho.
You really only need a caching SSD(s) if you need to fill up 10GB Ethernet.
Note that it is unlikely you'll get more than 30megabytes/s with the HP Proliant with the standard NIC card. The standard one isn't well supported in any OS but Windows. If you replace it with an Intel NIC (there is a R400 one that is PCI-Express x1 that will fit in the HP) you can probably get close to maximum speed for Gigabit Ethernet depending on the type of hard-drives you fit and the ZFS options you go for.
The Drobo's a bit too costly and the MicroServer can't expand when I fill it within 24 months. That leaves another internal drive with an external mirror - it's the cheapest of the lot, the most "repair friendly", but not the most reliable, and I'll still have 1 SATA port left for a 4TB in two years time. After that my PC will be due for replacement anyway. Pity. I was hoping to set up a reliable, resilient NAS for the whole network. I'll just keep streaming media from my PC.
Why don't you just get 5 drives and go for RAID-z1?
Last edited: