3 ms·

> Is it more likely that one of three drives in the degraded raidz1 fails during resilvering or that the one drive in the degraded mirror fails? That is a tough

> Is it more likely that one of three drives in the degraded raidz1 fails during resilvering or that the one drive in the degraded mirror fails? That is a tough question to answer Not that tough. If the load of 4 drives working bring them to malfunction then resilvering by pairs only prolongs the agony a bit and technically you are now 2 (or even 3 or 4) times more susceptible to a failure during rebuild (foreach stripe what would fail). > Hence my thrice-repeated desire to use the ability to swap new drives into old vdevs to mix ages, and my mixed-brand vdevs, as described in the root of this thread. LVM allows that without limits imposed by ZFS. Not applicable for your setup, sure. > , and also to realize performance benefits we have discussed upthread Depends on the workload. I had very good response from RAID0/10 SATA setups a decade ago (even from WD Greens), nowadays I find it inadequate for the current bloat. > A lot of the rest of the non-critical data is media that could be re-ripped from physical media (DVDs, Blu-rays). Understandable. > So, why do you care so much about my specific storage setup? Mostly idle curiosity. Especially with my first take (using LVM) is just inapplicable for you. > Does it pass muster yet, or am I still someone who is wrong on the internet to you? Harsh. But besides the idle curiosity I'm interested in other people setups and in giving a free, no strings attached, advice[0]. To sum up your setup from my POV: You are running a RAID10 setup to have the benefits of a slightly faster disk access and ease of resilvering. If there was a need to do something with this setup (and not limited to ZFS), I would consider the following: use a part of the disks as a RAID5 (3+1) for the WORM-like data (ripped DVDs, installers etc): greater SEQ and RND access, more usable space running RAID11 for the super critical data (so you can really lose 3 drives until you lose redundancy) there are also an option to run one mirror and another mirror or two simple volumes to have a protection against the logical failure, but you have ZFS snapshots which covers this use-case, for the most part Of course this is just fishes for though at best and again with ZFS (and [1]) there is not that much leeway, less the need to do anything. [0] heh [1] https://news.ycombinator.com/item?id=37190493 https://news.ycombinator.com/item?id=37190493

greggyb 3y ago
Thanks for the quiz and free advice. I'll ask you a few questions in return: does it seem like I have not put a fair bit of thought into my storage needs? Do I seem ignorant of disk topologies and their tradeoffs? In fact, I have run LVM as a storage manager in the past. There are many reasons I prefer ZFS. It is more rigid in some ways, and the benefits outweigh the bit of vdev inflexibility that I have to put up with. Perhaps understanding these preferences would be worthwhile before trying to tell me how to improve. Frankly, you come across as trying to convince me that I am wrong and that you know better. There were several points that I brought up repeatedly which you have dismissed out of hand. As just one example, you insist on dismissing the benefit of improved random IOPS, despite admitting that there is a measurable improvement when running a pair of mirrors; I stated several times that it is objectively better (which you never debated) and I experience a subjective improvement in responsiveness (which you repeatedly dismiss as trivial, negligible, or otherwise unimportant. Regardless of any difference of opinion, flatly dismissing what I have to say is not a great approach to educating or advising. Forcing me to repeat myself without actually addressing the point is rude at best. So, given that you clearly do not listen to me, I will treat your advice as worth exactly what I paid for it. And I hope you will forgive me if I do not consider repeating the same ideas and dismissing what I have to say as "idle curiosity". I do not say this out of malice. I have no reason to believe your intent is anything other than you say, but your intent is irrelevant; the effect of your communication is as I have described above. Hopefully someone else reading this thread will learn something.

greggyb 3y ago

Thanks for the quiz and free advice. I'll ask you a few questions in return: does it seem like I have not put a fair bit of thought into my storage needs? Do I seem ignorant of disk topologies and their tradeoffs? In fact, I have run LVM as a storage manager in the past. There are many reasons I prefer ZFS. It is more rigid in some ways, and the benefits outweigh the bit of vdev inflexibility that I have to put up with. Perhaps understanding these preferences would be worthwhile before trying to tell me how to improve. Frankly, you come across as trying to convince me that I am wrong and that you know better. There were several points that I brought up repeatedly which you have dismissed out of hand. As just one example, you insist on dismissing the benefit of improved random IOPS, despite admitting that there is a measurable improvement when running a pair of mirrors; I stated several times that it is objectively better (which you never debated) and I experience a subjective improvement in responsiveness (which you repeatedly dismiss as trivial, negligible, or otherwise unimportant. Regardless of any difference of opinion, flatly dismissing what I have to say is not a great approach to educating or advising. Forcing me to repeat myself without actually addressing the point is rude at best. So, given that you clearly do not listen to me, I will treat your advice as worth exactly what I paid for it. And I hope you will forgive me if I do not consider repeating the same ideas and dismissing what I have to say as "idle curiosity". I do not say this out of malice. I have no reason to believe your intent is anything other than you say, but your intent is irrelevant; the effect of your communication is as I have described above. Hopefully someone else reading this thread will learn something.