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Generally speaking newer kernels are considerably more stable than older kernels - the main reason Redhat and variants have such old Kernels is because of the p

by mrmondo 12y ago

Generally speaking newer kernels are considerably more stable than older kernels - the main reason Redhat and variants have such old Kernels is because of the proprietary driver compatibility and patches for 'enterprise' hardware such as RAID controllers. Additionally - there is also a trap where software is deployed that has been developed without the idea of being modernised (and in some cases maintained) over time - Vendors will often charge large amounts of money to modernise and test these applications. I've observed this as both a means of increasing profitability, out of lack of quality engineering / development skills or practices or by misinforming customers to think that risk aversion and a slow rate of change is the least costly option over time which leads to or is caused by pathological or bureaucratic organisational culture.

kbenson 12y ago
Generally speaking newer kernels are considerably more stable than older kernels That may be generally true of kernels, but when you are guaranteeing compatibility and support for a set of hardware, I would argue that after you've confirmed they work for a kernel, freezing that version and back-porting fixes and features that are worth it with another testing cycle is generally more stable.
- mrmondo 12y ago
  Can you give me an example of some hardware that is in general use that is no longer supported in Kernel 3.18/3.19? (I'm not saying you can't - I'm genuinely interested in this question)
  - kbenson 12y ago
    It's not that it's not supported, it's that the driver may have been modified to support other devices, or a portion could have been rewritten, and that could lead to short-term instability until they identify and fix any problems introduced.
  - pgaddict 12y ago
    It's not just about removing support for hardware - that happens from time to time, but generally not with reasonably recent hardware. It's also about minimizing risk of bugs in the new parts - even if you do a very thorough testing, you can't really eliminate the risks, so the more conservative deployments simply keep the old kernel versions. I do have my own experience with this, particularly with 3.10 - we've thoroughly evaluated it, yet after a few days on production all the machines crashed because of deadlock in the I/O stack. Very time consuming to debug where the actual problem is (virtualised environment, ...). So while I run Gentoo on most of my personal machines, I do understand why people are conservative.

by mrmondo 12y ago

kbenson 12y ago

Generally speaking newer kernels are considerably more stable than older kernels That may be generally true of kernels, but when you are guaranteeing compatibility and support for a set of hardware, I would argue that after you've confirmed they work for a kernel, freezing that version and back-porting fixes and features that are worth it with another testing cycle is generally more stable.

mrmondo 12y ago
Can you give me an example of some hardware that is in general use that is no longer supported in Kernel 3.18/3.19? (I'm not saying you can't - I'm genuinely interested in this question)
- kbenson 12y ago
  It's not that it's not supported, it's that the driver may have been modified to support other devices, or a portion could have been rewritten, and that could lead to short-term instability until they identify and fix any problems introduced.
- pgaddict 12y ago
  It's not just about removing support for hardware - that happens from time to time, but generally not with reasonably recent hardware. It's also about minimizing risk of bugs in the new parts - even if you do a very thorough testing, you can't really eliminate the risks, so the more conservative deployments simply keep the old kernel versions. I do have my own experience with this, particularly with 3.10 - we've thoroughly evaluated it, yet after a few days on production all the machines crashed because of deadlock in the I/O stack. Very time consuming to debug where the actual problem is (virtualised environment, ...). So while I run Gentoo on most of my personal machines, I do understand why people are conservative.