Nexenta is based on Solaris, which is the home-base of ZFS. FreeNas and ZFSGuru are based on BSD.
It is amazing that FreeNas 8.3 can keep up with Nexenta now. ZFSGuru can´t keep up with the other two and according to the benchmarks the difference is quite big. The makers of ZFSGuru are looking now if there is a benchmark error or it is because of the version (0.2 Beta 7) used in the benchmarking. Since ZFSGuru comes with a full version of FreeBSD, there are a lot of possibilities of tweaking with the commandline.
However, I personally prefer FreeNas on a production system since ZFSGuru is still more in development (but stable according to many users), missing alot of features in the GUI, and they (still) are missing a good manual (like FreeNas 8) which makes life for noobs like me easier.
A quick word about RAIDZ, like I promised many posts ago.
What is RAIDZ?
RAID-Z is not actually a kind of RAID, but a higher-level software solution that implements an integrated redundancy scheme similar to RAID 5, using ZFS.RAID-Z avoids the RAID 5 “write hole” using copy-on-write: rather than overwriting data, it writes to a new location and then automatically overwrites the pointer to the old data. It avoids the need for read-modify-write operations for small writes by only ever performing full-stripe writes. Small blocks are mirrored instead of parity protected, which is possible because the file system is aware of the underlying storage structure and can allocate extra space if necessary. RAID-Z2 doubles the parity structure to achieve results similar to RAID 6: the ability to sustain up to two drive failures without losing data. (source wikipedia)
This means in plain language:
RAIDZ is comparable with RAID5: e.g. you need minimum of 3 discs. If 1 disc will crash, your data will still be safe. If more than 1 disc will crash you will loose your data.
RAIDZ2 is comparable with RAID6: you need a minimum of 4 discs. If 1 o 2 discs will crash, your data will still be safe. If more than 2 discs will crash you will loose your data.
RAIDZ3 don´t exist as a physical RAID: you need a minimum of 5 discs .If 1-3 discs will crash, your data will still be safe. If more than 3 discs will crash you will loose your data.
RAIDZ 3,5 and 9 discs.
RAIDZ2 4, 6 and 10 discs.
RAIDZ3 5, 7 and 11 discs.
My ZFS is now running about 3 weeks without problems. I will tell more about it next time
Next to my work as an emergency doctor, I also am a general practitioner of a special kind of boarding school with juvenile delinquents, children from disrupted families, etc … It is not a prison. the children can go home in the weekend, if they behave well.
Part of their treatment consists of working and learning in the nature. So the centre constructed a ¨petit zoo¨ together with their boys. Up til now they have some regular animals like ducks, pigs etc. But today they have a new member: