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On Thu, Dec 7, 2017 at 9:53 AM, Frank Steinmetzger <Warp_7@×××.de> wrote: |
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> |
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> I see. I'm always looking for ways to optimise expenses and cut down on |
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> environmental footprint by keeping stuff around until it really breaks. In |
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> order to increase capacity, I would have to replace all four drives, whereas |
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> with a mirror, two would be enough. |
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> |
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That is a good point. Though I would note that you can always replace |
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the raidz2 drives one at a time - you just get zero benefit until |
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they're all replaced. So, if your space use grows at a rate lower |
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than the typical hard drive turnover rate that is an option. |
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> |
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> When I configured my kernel the other day, I discovered network block |
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> devices as an option. My PC has a hotswap bay[0]. Problem solved. :) Then I |
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> can do zpool replace with the drive-to-be-replaced still in the pool, which |
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> improves resilver read distribution and thus lessens the probability of a |
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> failure cascade. |
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> |
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If you want to get into the network storage space I'd keep an eye on |
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cephfs. I don't think it is quite to the point where it is a |
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zfs/btrfs replacement option, but it could get there. I don't think |
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the checksums are quite end-to-end, but they're getting better. |
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Overall stability for cephfs itself (as opposed to ceph object |
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storage) is not as good from what I hear. The biggest issue with it |
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though is RAM use on the storage nodes. They want 1GB/TB RAM, which |
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rules out a lot of the cheap ARM-based solutions. Maybe you can get |
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by with less, but finding ARM systems with even 4GB of RAM is tough, |
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and even that means only one hard drive per node, which means a lot of |
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$40+ nodes to go on top of the cost of the drives themselves. |
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Right now cephfs mainly seems to appeal to the scalability use case. |
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If you have 10k servers accessing 150TB of storage and you want that |
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all in one managed well-performing pool that is something cephfs could |
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probably deliver that almost any other solution can't (and the ones |
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that can cost WAY more than just one box running zfs on a couple of |
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RAIDs). |
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-- |
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Rich |
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