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Old 25th March 2014
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vermaden vermaden is offline
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Quote:
Originally Posted by Oko View Post
A quick look will show that at least 8GB of RAM is required for any kind a serious data storage more like at least 1 GB for each TB of physical storage plus 1GB per each core.
That depends what are your requirements ... if You want to serve 40 TB of data simultanousely to 100 users, then You need more RAM, more CPUs, probably ZFS mirror on SSDs for ZIL device and one or more SSDs for L2ARC ZFS read cache ... but if You have ~1.5 TB of data and You use it as NAS in home environment for 3-4 devices at most, then 1 GB of RAM is OK.

Quote:
Originally Posted by Oko View Post
Also you do not even have enough disks to really run ZFS with any kind redundancy and data protection.

This is official FreeNAS recommendation:
  • Start a RAIDZ1 at at 3, 5, or 9, disks.
  • Start a RAIDZ2 at 4, 6, or 10 disks.
  • Start a RAIDZ3 at 5, 7, or 11 disks.
I use ZFS MIRROR for redundancy (2 disks), which is like RAID1, so I have redundancy, if one disk fails, then the data is accessible from the other one.

ZFS also has an optimalization where in mirror data are read simultanousely from both drives, so its more like RAID1 for writes and RAID0 for reads.

RAIDZ1 is like RAID5 (but without write hole problem) with 1 disk for parity, RAIDZ2 for RAID6 with 2 disks for parity and so on.


Quote:
Originally Posted by Oko View Post
Personally I would never run ZFS at home.
Why?

Quote:
Originally Posted by Oko View Post
Now your hardware looks like a perfect hardware for 2TB Hammer storage with mirroring running of DragonFly BSD but you already knew that.
From what I remember HAMMER does not keep sha checksums of all blocks, so it does not make sure that data is not corrupted.

ZFS does have sha checksums for all blocks and if any checksum does not match, then it will be fixed from the other disk.

If I would build ZFS for serious work on the datacenter with tens of terabytes I would probably would use something like Storage Pod with several SSDs for ZIL and L2ARC.
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