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Jack wrote: |
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> On 2019.01.07 05:46, Dale wrote: |
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>> Peter Humphrey wrote: |
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>> > On Sunday, 6 January 2019 22:13:31 GMT Dale wrote: |
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>> > |
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>> >> Even from my simple setup, LVM adds more benefits to managing data |
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>> and |
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>> >> drives than it does risk. The biggest thing, placing blame where it |
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>> >> lies. Blaming LVM for a drive dying is placing the blame on |
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>> something |
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>> >> that wasn't the root of the problem. The dying drive was the |
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>> problem, |
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>> >> using LVM or not. |
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>> > He isn't doing that, though. As I read it, he recounted the tale of |
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>> recovering |
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>> > data from a failed drive, then imagined how much worse it would be |
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>> if it were |
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>> > in an LVM setup. [Reported speech and mixed-up tenses causing me a |
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>> problem |
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>> > here...] |
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>> > |
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>> > Thanks Gevisz, that was interesting. What we used to call a |
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>> cautionary tale. |
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>> > |
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>> |
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>> From what I've read, that can be overcome. If you get say a SMART |
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>> message that a drive is failing, just remove that drive or remove the |
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>> whole LVM setup and use something else until a working drive setup can |
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>> be made. Once ready, then move the data, if the drive still works, to |
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>> the new drive. That is basically what I did when I swapped a smaller |
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>> drive for a larger one. I moved the data from one drive to another. It |
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>> did it fairly quickly. Someone posted that it may even be faster to do |
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>> it with LVM's pvmove than it is with cp or rsync. I don't know how true |
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>> that is but from what I've read, it moves the data really efficiently. |
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>> If the drive has a very limited time before failure, speed is |
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>> important. If the drive is completely dead, replace the drive and hope |
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>> the backups are good. Either way, LVM or not, a failing drive is a |
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>> failing drive. The data has to be moved if the drive still works or the |
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>> data is gone if it just up and dies. The biggest thing, watching the |
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>> SMART messages about the health of the drive. In the past when I've had |
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>> a drive fail, I got error messages well ahead of time. On one drive, I |
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>> removed the drive, set it aside, ordered a replacement drive, installed |
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>> both drives and copied the data over. After I did all that, I played |
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>> with the drive until it failed a day or so later. Lucky? Most likely. |
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>> Still, it gave me time to transfer things over. |
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>> |
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>> While I get that LVM adds a layer to things, it also adds some options |
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>> as well. Those options can prove helpful if one uses them. |
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>> |
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>> Just my thinking. |
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>> |
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>> Dale |
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> The only problem with all that is that SMART is far from completely |
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> reliable. I recently had a drive fail, and the resulting fsck on the |
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> next reboot messed up many files. (Not a Gentoo system, although I |
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> don't think that made any difference.) After getting running again, I |
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> did several SMART tests, including the full self-test, and it reported |
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> ZERO errors. A few weeks later, it did the same thing, and shortly |
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> after that, it failed totally. I had done a few more full self-tests |
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> before final failure, and all came back clean. I'd really love to |
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> find out there was something I did wrong in the testing, but I don't |
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> think so. I have not yet completely given up on trying to recover |
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> stuff from that drive, but as time goes on, there is less and less |
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> that I haven't rebuilt or replaced by re-downloading or changing lost |
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> passwords, so it's less and less important. (That was a different |
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> drive from the one I messed up myself, as discussed in another recent |
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> thread here.) |
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> |
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> Jack |
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> |
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But do you have any other way to get a warning? It may not work every |
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time, especially if the spindle motor just up and dies all of a sudden |
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but it does detect some errors. It is certainly better than having |
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nothing at all. So far, SMART has detected errors and warned me for the |
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two drives I've had fail. My neighbor had a drive to fail and it gave |
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warnings as well, during boot up but SMART still spit our errors. Thing |
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is, the owner ignored it until it wouldn't boot anymore. By that time, |
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it was toast. They ran windoze. When SMART does warn, it pays to |
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listen. ;-) Mine emails me when any error is reported. |
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|
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Thing is, a bad drive will always risk the loss of data. Always has. |
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Monitoring SMART is better than nothing and generally gives some |
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warning. It's not perfect but there is nothing else that does any |
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better that I've heard or read about. It's the reason everyone should |
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back up data they can't afford to lose. |
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|
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Dale |
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:-) :-) |
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