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6

You shouldn't use non-ECC RAM on any machine that is storing or processing data you care about. This is not something that is unique to ZFS. You're right, ZFS devs have gone to great lengths to add many layers of hashing, verification, etc. to the filesystem - all of these are of massive help in ensuring data integrity, and all of these efforts can be ...


6

OH MY! How embarrassing ... I found the reason ... The pool (old-pool) I am trying to replicate is itself a backup store, receiving regular updates via zfs receive -F So while my recursive snapshot was initially complete, it got "cleaned out" as new snapshots were being integrated into individual filesets. Once I stopped the backup script that was ...


3

More modern versions of ZFS provide a command named zstreamdump which can provide human-readable information from a stream (or image) created using zfs send. This is an example using the commandline: host # zstreamdump < foo.zfs BEGIN record ... toname = zpool/data/foo@04hoursago END checksum = ...


3

Note: using a hot spare in this situation probably is not the best idea. See below for the reasoning behind that, below the answer to the question as asked. The answer to the question as asked: Before reducing the pool redundancy, I strongly suggest letting one complete scrub run to ensure that all devices are functioning and that there are no latent ...


2

It's a bad idea to use a disk as a spare in this setup: you will lose the third disk read speed gaining almost nothing in write speed. The key point to understand is that writes are written concurrently, so there is (almost) no slowdown on having a 3-disk mirror vs a 2-disk one.


2

If using FreeBSD (also FreeNAS) read speed is better. Source: http://open-zfs.org/wiki/Features#Improve_N-way_mirror_read_performance Linux/illumos/OSX does not have that patch which rebalances read I/O to the least busy device, instead it's just round-robin. With these, you will still get a performance boost with a n-way mirror vs. single drive, but in ...


1

Short of patching your kernel, I don't think you can. During shutdown, the scsi disk driver issues a SYNCHRONIZE CACHE command to flush the disk's internal cache. This will cause the drive to spin up, then the drive is spun down again before shutting down.


1

No. The disks are raw and portable when used with a pure SAS HBA like the LSI-9211. There's no RAID metadata involved here. Also see: ZFS SAS/SATA controller recommendations


1

This depends on the ZFS implementation and the Hardware you are using. These benchmarks https://calomel.org/zfs_raid_speed_capacity.html provide a quick overview of the mirrored/striped performance, measured on FreeBSD. As you can see, the read performance is doubled with SSDs and increased by approximately 50% with HDDs.


1

NAME STATE READ WRITE CKSUM projects FAULTED 0 0 1 gptid/49d49544-5a47-11e2-b516-00259095142c ONLINE 0 0 0 gptid/49f3c886-5a47-11e2-b516-00259095142c ONLINE 0 0 2 gptid/4a1052aa-5a47-11e2-b516-00259095142c ONLINE 0 0 ...


1

I would argue that running FreeNAS with non-ECC RAM is a stupid idea, as is running it as a virtualized guest, when the data stored on the ZFS volume is important. Joshua Paetzel, one of the FreeNAS developers, has a good write-up on this topic: ...


1

Download a new .iso file from thier site. It seems to be a problem with the image


1

The idea of sync writes is really a good idea for boot disks, which are key to virtualization. You want to wait for an acknowledgement. Speed is not an issue at boot, durability should be. When you need performance, go to something speedier. Performance and reliability are always a tradeoff. On of my pet peeves is when people want really speedy VM ...


1

I believe the reason why you are seeing things like errors: Permanent errors have been detected in the following files: <0x7c343>:<0x45b6bcd> is because the data still exists in a snapshot, and only a snapshot. Remember that a snapshot in ZFS is only a point-in-time marker; it does not actually copy any blocks, it simply keeps the ...



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