>>>>> "Redeeman" == Redeeman <redeeman@xxxxxxxxxxx> writes: >> Consider also how many people complain about botched rebuilds due >> to multiple drive failures on rebuilds and bad blocks on surviving >> disks. I can't remember anybody who bought enterprise class disks >> asking for such help recently, it always seems to be people who buy >> consumer drives. No wonder several fail within days of each other, >> they all have same model, I/O load, and generally same >> manufacturing batch. Redeeman> Did you ever split open the consumer and "enterprise" Redeeman> versions of the drives and observe? Redeeman> While i do believe they do some more testing/quality control Redeeman> on the enterprise disks, they are almost all identical Redeeman> excepting firmware.. so to be fair, i'd say the mistake is Redeeman> not properly stress testing the disks, and for instance just Redeeman> buying a huge batch of disks and putting to use.. People always seem to assume that hardware is what's making the difference between consumer and enterprise. It's not. The physical hardware differs mostly due to capacity vs. RPM trade-offs. Most vendors these days have big platters for high-capacity drives and smaller platters for high RPM/higher IOPS class drives. On top of that, head/platter count may vary in capacity classes within a series. But the important difference between consumer and enterprise drives is not mechanical. It's the firmware. Consumer drive firmware is about squeezing out the most capacity/$ and nothing else. Enterprise drives trade capacity for reliability by way of the firmware. That includes many things like using more space for track info (gap/sync), much better ECC, better tolerance for rotational vibration, etc. Most of the errors you see on drives are a result of media errors that are big enough that the drive ECC can't correct them. Errors are often caused by head misses due to bad tracking, vibration from other drives in the enclosure, the user kicking the cabinet at an inopportune moment, etc. I.e. external interference. Other errors are due to real imperfections of the media itself. Enterprise drive firmware is about being more resistant to outside factors as well as real media defects. That firmware cost more to develop than the consumer ditto. And the vendors charge a premium for it. So it's not the size that matters. It's how you use it. -- Martin K. Petersen Oracle Linux Engineering -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
