ZFS: Use mirror vdevs, not RAIDZ
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ZFS: Use mirror vdevs, not RAIDZ
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Re: ZFS: Use mirror vdevs, not RAIDZ
#2"Use RAID10" is basically the storage equivalent of "use paper ballots". Sure, it feels suboptimal, but critically your intuition on how it can fail (mostly) works. That's a really nice property to have for storage.
Re: ZFS: Use mirror vdevs, not RAIDZ
#3Parity pools are for poors. Mirror pools are for chads.
Re: ZFS: Use mirror vdevs, not RAIDZ
#4For big installations i do striped (sometimes mirrors) vdevs (2 disks) and on top of them Raidz2/3. Works fast as hell and reliable.
Re: ZFS: Use mirror vdevs, not RAIDZ
#5I had my pitchforks out because I really like my raidz1 setup, but the arguments are very good for the mirror. When I set my pool up, I chose raidz1 because compared to mirroring, I still have 37.5% more space, which is huge if the budget is constrained. But if you feel paranoid and the raidz3 begin to sound good, that 12.5% extra space doesn't seem to worth the extra complexity over a much straightforward mirror.
Re: ZFS: Use mirror vdevs, not RAIDZ
#6> don’t be greedy. 50% storage efficiency is plenty.
LOL.
Re: ZFS: Use mirror vdevs, not RAIDZ
#7> don’t be greedy. 50% storage efficiency is plenty. LOL.
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Re: ZFS: Use mirror vdevs, not RAIDZ
#8As always with RAID-style setups, there’s an inevitable trade off of cost vs capacity vs performance.
There’s still a place for RAIDZ/RAIDZ2, and in my opinion that place is storing bulk data that isn’t too heavily accessed or that needs to be stored with an eye towards keeping £/GB down.
Yes, mirrors are faster. Yes, mirrors are easier to expand. But across 12 4TB disks that is 24TB instead of 40TB with RAIDZ2 - and that’s a lot of capacity to lose if you’re on a budget.
The rebuild times in this post seem high to me, though. I replaced 7x 2TB disks (nearly full) in a raidz1 in a backup pool with larger drives in about 30 hours.
Re: ZFS: Use mirror vdevs, not RAIDZ
#9Every time I make this argument (whether regular RAID or ZFS), everyone pulls out their pitchforks and tells me about how they have run RAID 5 or 6 for years and never had a problem, plus "I can have two drives fail! You would lose your array if the wrong two drives fail!"
But drive failure is much more likely during an operation like a resilver/resync, and I wonder if the majority of people espousing more risky RAID a setups (especially single parity) are those who just want hundreds of TB for a growing media collection.
I know for my critical data, I don't trust parity. Plus I can't afford the days or weeks long resilver operation, I need a working storage array that doesn't suffer drastically in performance if one drive goes bad.
Re: ZFS: Use mirror vdevs, not RAIDZ
#10My gripe with this is that the author assumes everyone has the same workload and prefers the same set of tradeoffs. I use raidz1 on my home desktop precisely because I would absolutely prefer to have to wait for a resilver than lose data.
“So backup your data!” - of course, but that’s just an implicitly larger pool.