I found that we have currently separate tags for the different levels of raid : raid0, raid5, raid1. So, should they be merged into the main tag: raid, or do they provide necessary additional information?
3 Answers
They have different performance and redundancy characteristics.
Probably more importantly here, they have different steps to handle recoverable failures, different things to attempt recovery in a disaster, different steps required to to boot from them (e.g., RAID1 can boot w/o special bootloader support, RAID0, 4, 5, 6, can not). So, you often need to know the RAID level(s) involved to answer.
Personally, I view tags as largely about directing questions to the appropriate experts. I'm not sure if there are experts in a particular RAID level—so as a tag to follow, they fail.
However, others view tags as about categorization (and I personally think that's a good secondary use), and raid levels appear to be perfectly valid categorization. Also useful, I suppose if you're searching for a question about booting from RAID5.
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2There should have been implemented link in one direction, from raidX to raid, so that if someone tagged a question raid5 then bare raid would be already involved (no need to add it), and "experts" informed.– jimmijCommented Jan 11, 2016 at 1:03
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"So you often need to know the RAID level(s) involved to answer." —This is the key point. Somewhat like we have separate tags for ext2, ext3, ext4. Sure, they're all "ext" but that doesn't make them very similar—and if that was the only information given, many questions with that tag would be unanswerable. Upvoted.– WildcardCommented Jan 12, 2016 at 8:29
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All categorisation is a compromise, there's always a use case where a specific categorisation approach fails. In this instance, I take the approach that RAID5 questions are generally different from RAID1 questions, and questions about RAID (non-specific type) are more likely (in my view) to be broad, opinion or general queries (is RAID good, why do we have RAID, etc.). Commented Jan 13, 2016 at 13:30
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In my opinion (as a storage engineer, so appreciate my perspective might differ from most of U&L):
RAID variant is a configuration detail. If you are here asking a question about RAID, then there are other configuration details more important than the RAID mode. Like hardware platform, OS, controller type, HBA model, disk tech.
These are usually more significant details in filtering a question about RAID, and as such I would suggest they would be worth synonym-ising to raid
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4I think your perspective is right when dealing with hardware RAID where regardless of the RAID level, it just shows up as a single block device. And if your SAN had a catastrophic failure, you'd probably call your vendor or ask Serverfault. But most of the site is probably using mdadm and software RAID, and we fairly regularly get questions about recovering from disasters.– derobertCommented Jan 13, 2016 at 15:30
Having built RAID 0, 1, 5, 6, and just recently RAID-10 arrays in Kali Linux, I found the differences in each class to be very interesting. My usb is needed of course to boot up my RAID-10, and two of the RAID arrays I built inside the usb, which incidentally is 65 Gigs. The difference in performance in my system now is indeed noteworthy after going from RAID-6 to RAID-10. I'm the new guy here, and it looks like I've already pissed someone off, oops. Anyways, I don't see any harm in having separate, specific tags for each structure.