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Adding more disks to it. The thing is that disks used in RAIDs tend to be of the same model and even batch and thus suspicious to the same vulnerabilities. Home

by mrjin 5y ago

Adding more disks to it. The thing is that disks used in RAIDs tend to be of the same model and even batch and thus suspicious to the same vulnerabilities. Home users typically don't really have neither the need of the capacity/speed nor the budget to allow enough disks in the RAID to allow two disks failing at the same time. As disks get larger and larger, it's really unlikely to have no defects for all disks during the expected life span of the RAID. If one disk in the array shows signs of failure, the others probably going to have the exact the save issue soon. Given the size of the disks, it can take days to rebuild the array after replacing a single failed disk. Making it worse, rebuilding itself also put more pressure on the remaining disks that might be imminent to fail and can really lead to a cascading failure of multiple disks, in which case, total loss of data is unavoidable. So even my NAS supports RAID5/6, I still go with single disk volumes so that in event of disk failures I'll only have to replace the failed disks and lose only the data on it in the worse case. In fact, I don't lose much because my data does not have to be in the same volume and the disks are ready fast enough and made my home network the bottleneck.

foxrider 5y ago
Recently my small home server had a disk failure. One of the BTRFS RAID0 drives started having a lot of device errors, and shortly after the second drive started having errors too - but BTRFS was able to just take the healthy bits from both disks and I lost nothing. However, since I had to now replace 2 disks I decided an upgrade would be in order, the disks been there for 10 years and I wanted to have more that 1tb for a while. Turns out it's two times cheaper to have a 4tb array with 3 2tb disks than a 4tb array with 2 4tb disks.
- mrjin 5y ago
  Well, I would say you had bad sectors on your disks, if there weren't too many of them, most modern file systems can handle it but still there are possibilities of losing data. But nonetheless, it's a signal to start migrating data. What I meant for disk failures was really disk failures, there would be no way directly get data out of the disk unless you open it and directly read the plates, in your case, all your data would be totaled as RAID0 offers no redundancy and thus tolerates no single disk failures at all. Your data seems not much and it would not be that hard to migrate a 4TB array. Things would be completely different if you will have to rebuild more even worse migrate a much bigger array i.e. 4x10TB ones. Even if everything goes on well, it will take a few days just to copy the data somewhere else. If there were cascading failures, then there is really not much you can do. I can promise you that once you went through all those nightmare, you will never ever want to do it again. Take into those cost/effort needed, whenever I need to build a personal NAS, I always go with 2/3 biggest capacity NAS/Enterprise HDDs available and leave at least 1 vacant bay so that I can easily add more space without fiddling with existing drives. Even if the NAS eventually become full, I can still simply replace smallest drive with a bigger one and copy the data back.

by mrjin 5y ago

foxrider 5y ago

Recently my small home server had a disk failure. One of the BTRFS RAID0 drives started having a lot of device errors, and shortly after the second drive started having errors too - but BTRFS was able to just take the healthy bits from both disks and I lost nothing. However, since I had to now replace 2 disks I decided an upgrade would be in order, the disks been there for 10 years and I wanted to have more that 1tb for a while. Turns out it's two times cheaper to have a 4tb array with 3 2tb disks than a 4tb array with 2 4tb disks.

mrjin 5y ago
Well, I would say you had bad sectors on your disks, if there weren't too many of them, most modern file systems can handle it but still there are possibilities of losing data. But nonetheless, it's a signal to start migrating data. What I meant for disk failures was really disk failures, there would be no way directly get data out of the disk unless you open it and directly read the plates, in your case, all your data would be totaled as RAID0 offers no redundancy and thus tolerates no single disk failures at all. Your data seems not much and it would not be that hard to migrate a 4TB array. Things would be completely different if you will have to rebuild more even worse migrate a much bigger array i.e. 4x10TB ones. Even if everything goes on well, it will take a few days just to copy the data somewhere else. If there were cascading failures, then there is really not much you can do. I can promise you that once you went through all those nightmare, you will never ever want to do it again. Take into those cost/effort needed, whenever I need to build a personal NAS, I always go with 2/3 biggest capacity NAS/Enterprise HDDs available and leave at least 1 vacant bay so that I can easily add more space without fiddling with existing drives. Even if the NAS eventually become full, I can still simply replace smallest drive with a bigger one and copy the data back.