morfizm (morfizm) wrote,

Want FreeNAS+ZFS as a home server? Think twice.

FreeNAS+ZFS summary (vs WHS) -- assuming you want to approach 1GBit/sec seq read/write bandwidth:

• Pro: RaidZ out of the box: software RAID with both redundancy and performance.
• Pro: software mirroring implemented with true read performance boost (forums say close to double but I haven't tested).
• Pro: It has end-to-end check-summing and auto-correction single read errors in RaidZ/RaidZ2 arrays. Periodic "scrubs" will just read the entire array, thus causing auto-correction if necessary.
• Pro: Encryption supported, encryption and compression are fast. (You should have strong CPU though. But you should have it regardless).

• Con: Overall ZFS is tuned for enterprise multi-user environment, and things like VMs and Oracle databases accessed straight from server. Be ready to discover more unwanted surprises for "a home server with a few users" scenarios. For any home-user-only feature request, FreeNAS developers will just laugh at you.
• Con: Server requires strong CPU. At least quad core with high clock. No micro servers.
• Con: Server requires plenty of ECC RAM. For 8T array, 16 GB is a minimum. (+$180).
• Con: Doesn't do defrag, and it does copy on write. It's compensated with necessity for ZIL for write buffering and lowering IO sync impact, and L2ARC for cache and read-ahead.
    ○ Requires 3 small SSD drives (1 for L2ARC and 2 mirrored for ZIL). (+$150).
    ○ L2ARC SSD shouldn't be very large - or pay with significant ARC space (ECC RAM) to keep metadata. Metadata to data ratio is 1/45 (120GB disk will require 2.7GB of RAM).
• Con: Allows upgrading disks but only lets you use extra space once ALL disks in array were upgraded (min size used).
• Con: You can boot the OS from USB drive. Any other options aren't really supported. 2.5GB is used and other flash space is unusable by design. Upside: easy to upgrade (you can export config and just plug an updated thumb drive).
• Con: Encryption require manual intervention to unlock the drive (or do some scripting, be careful with security).
• Con: You aren't supposed to run your own arbitrary extra server-type jobs on FreeNAS (pain in the ass to configure and maintain).
• Con: You should have >30% of free space or performance will suck.
• Con: Samba/CIFS support for Windows shares are very slow on metadata reads (list directory). Use NFS. Windows understands NFS (haven't tested NFS yet).
• Con: Permissions are pain in the ass to configure.
• Con: NTFS is not fully compatbile. I observed loss of ChangeTime and loss of one decimanal place in LastWrite, LastAccess and CreateTime. This may cause trouble with sync tools like robocopy.
• Con: Server backup with rotating disks is difficult to configure (not yet done). Volume snapshotting can help with incremental backup scenario when you want to recover accidentally deleted files from server.
• Con: Deduplication is possible but requires 5GB of ECC RAM per 1TB of data (not sure dedupped or source, but I hope dedupped).
• Con: No "client backup" solution out of the box, you should use something else (e.g., again, WHS :)). However, if you use dedup, you can just do periodic full image backups or rsync your client drives. You'll lose perf benefit of "incremental" though, but preserve some space benefit.
Tags: 1, devices, in english, software

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