General > General Technical Chat
Replacement NAS
vad:
--- Quote from: Halcyon on April 14, 2024, 12:04:07 am ---
--- Quote from: vad on April 13, 2024, 08:01:35 pm ---Another vote for TrueNAS. I’ve been running FreeNAS (the old name of the free community version) and TrueNAS Core for over seven years without any issues or data loss. I currently have two servers: one old rack mounted DIY build and another TrueNAS Mini appliance from iXsystems.
Bear in mind that ZFS, with all its great features, is intolerant to crashes, and there is a near-zero chance of recovering a corrupt ZFS pool. So make sure you back up your unique data to another device or into the cloud. If you build your own NAS, pay close attention to hardware recommendations and best practices, such as ECC RAM, UPS.
--- End quote ---
Eh, I wouldn't bother with ECC RAM personally. It offers very little benefit. Even as a user who has a server rack and enterprise gear at home, if I was to rebuild my NAS, I wouldn't bother with ECC RAM. It really doesn't matter.
As for "intolerant to crashes", I strongly disagree. I've had servers simply switch off after the UPS battery dies, with no impact to the ZFS pool. ZFS is extremely resiliant. Even in cases of the underlying OS crashing, ZFS should remain intact. Severe file system damage (ZFS or otherwise) is usually either the sign of hardware problems, or user error (or both). For example, allowing the pool to degrade to such a point that you're forced to try and restore data from a failing hard disk in order to restore your pool.
ZFS is an extremely robust and resiliant file system. Would highly recommend it, but regardless, always have a backup of your data on seperate media. I still don't consider ZFS as a form of "backup", just like traditional RAID isn't.
--- End quote ---
Many decades ago, when I lived in Russia, there was a culture among drivers not to wear seatbelts. At my workplace, the chauffeurs took it as a personal affront if you dared to buckle up in the passenger seat, as if questioning their safe driving skills. They were seasoned professionals, with more years behind the wheel than they could count. They all presented a compelling argument: they claimed they had driven cars throughout their entire careers, and none of them had ever been injured in a car accident.
Can you run TrueNAS on non-recommended hardware and never suffer total loss of a ZFS pool? Sure, you can, if you're lucky enough. Should you run it on a machine with non-ECC memory and without battery power backup? That depends on many factors, such as how much you value your data, whether you have a backup, what your RTO and RPO are for your disaster recovery plan, and how much you value your time, keeping recovery time in mind.
If the NAS crashes before it syncs pending metadata changes to disks (where metadata stands for file allocation tables of the beautiful COW file system), your entire ZFS pool will be lost with little prospect of recovery. And unlike inferior NTFS, FAT32, and EXT file systems, you will not find any tool, commercial or open source, to salvage even a fraction of data from a bad ZFS pool.
But who am I to suggest you wear the seatbelts?
Halcyon:
--- Quote from: vad on April 14, 2024, 01:48:45 am ---If the NAS crashes before it syncs pending metadata changes to disks (where metadata stands for file allocation tables of the beautiful COW file system), your entire ZFS pool will be lost with little prospect of recovery. And unlike inferior NTFS, FAT32, and EXT file systems, you will not find any tool, commercial or open source, to salvage even a fraction of data from a bad ZFS pool.
--- End quote ---
That's the entire point of copy-on-write file systems, like ZFS. It's designed to withstand sudden power failures or incomplete writes, without catastrophic loss of data. Live, good data is never overwritten and that includes the metadata.
vad:
--- Quote from: Halcyon on April 14, 2024, 02:51:00 am ---
--- Quote from: vad on April 14, 2024, 01:48:45 am ---If the NAS crashes before it syncs pending metadata changes to disks (where metadata stands for file allocation tables of the beautiful COW file system), your entire ZFS pool will be lost with little prospect of recovery. And unlike inferior NTFS, FAT32, and EXT file systems, you will not find any tool, commercial or open source, to salvage even a fraction of data from a bad ZFS pool.
--- End quote ---
That's the entire point of copy-on-write file systems, like ZFS. It's designed to withstand sudden power failures or incomplete writes, without catastrophic loss of data. Live, good data is never overwritten and that includes the metadata.
--- End quote ---
Design and real-world use are different things. The Boeing 737 MAX was supposed to be a superior design over the 737NG. In real life, it proved to be a disaster. Even then, Sun Microsystems never intended for ZFS to run on a recycled, ancient desktop from a dumpster.
You may refer to TrueNAS community forums for hardware guides and horror stories from those who did not RTFM.
Edit: Also, all appliances from TrueNAS vendor iXsystems come with ECC memory.
Halcyon:
iXsystems' hardware requirements are quite broad. See: https://www.truenas.com/docs/core/gettingstarted/corehardwareguide/
They don't recommend ECC as a requirement, but says you can use it. Since their appliances are designed for enterprise, of course they would come with ECC RAM. Most, if not all, enterprise gear does.
I appreciate your analogies vad, but I don't think you're making a very strong argument. ZFS is a resilient filesystem by design and it's certainly lived up to that design in real-world applications for quite a long time.
If you can demonstrate ZFS pool corruption on a PC by simply yanking the power cord or causing the OS to crash, I'll stand to be corrected. Use the cheapest, crappiest hardware if you like, as long as it meets their requirements. However based on many years of experience in this industry, I haven't seen it happen unless there is some underlying cause that hasn't been addressed (which I usually chop up to user error). As they say, the proof is in the pudding. If you can show me that ZFS is "intolerant to crashes" (your words, not mine), then I will withdraw my earlier statements. And by "show", I don't just mean some vague forum post, anyone can cherry pick comments on the internet, but I mean actual proper evidence of this alleged weakness in ZFS.
You've already claimed that "If the NAS crashes before it syncs pending metadata changes to disks (where metadata stands for file allocation tables of the beautiful COW file system), your entire ZFS pool will be lost with little prospect of recovery" which is demonstrably false, so I'm sorry, I don't have a lot of faith in your advice.
nctnico:
I'd keep power consumption in mind. A pc in any form isn't particularly efficient.
Additionally modern nas systems have many extra features. I'm quite happy with a Qnap nas btw but that is only one data point.
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