Of course not. I've built several petabytes worth of storage systems in the past 15 years, OTOH.
> Using desktop drives, when 24 are mounted in a single chassis, the vibration from those drives will cause a higher rate of failure.
Absolutely. However this is not always directly applicable to all desktop drives. In fact I'm going to reveal a secret : physically, desktop SATA drives are exactly the same as professional grade 24/24h operation-guaranteed SATA drives. When they fall off the assembly line, they're tested for reliability and performance. Over a certain threshold, a drive is deemed professional and receive the pro firmware; under the bar, it's a desktop drive.
What is the most important difference between the desktop vs pro firmware? The desktop drive is supposed to be used alone. In case of an error, it will retry, retry and retry again endlessly to ecc-correct the error. OTOH, the pro drives "knows" it's part of a RAID array; at the slightest fault, it will simply cry "I'm failed" and give up. So in case of a transient error, your IOs won't be blocked.
There are some other differences depending upon the maker: for instance all Hitachi GST drives carry an accelerometer, but the desktop drive firmware don't know how to use it to compensate for low-frequency vibrations.
WD desktop drives have particular settings that make them extremely dangerous to use in RAID arrays.
Note that the "pro/consumer" threshold can be moved to reach some volume threshold regardless of the actual drive quality. This happened, I've been bitten.
Anyway, prefer the pro drives even if there 50% more expensive. It will save you some headaches.
> When a single drive in your 24 drive chassis fails, how do you know which one it is?
First, I suppose the maker (in my case, my team), carefully checked that all drives are properly labeled (so that drive 1 is labeled 1, etc); second, decent RAID controllers can flash a drive LED (Adaptec 5xx5 or 6xx5 series come to mind).
> Can you handle a double disk failure without losing data?
With drives of 1 TB or more, RAID-5 is definitely out and has been so for several years. RAID-6, RAID-6, RAID-6 is the way to go.
> These are things that enterprise storage vendors spend months with engineers designing.
E-xact-ly. BTW I'm an enterprise storage vendor. However I'm really too far from Louisville to be able to ship there and support it. I just mentioned what is possible; don't forget that nowadays, when you're buying an SGI (or many other big names) storage system you're buying Supermicro hardware.
> In fact I'm going to reveal a secret : physically, desktop SATA drives are exactly the same as professional grade 24/24h operation-guaranteed SATA drives. When they fall off the assembly line, they're tested for reliability and performance. Over a certain threshold, a drive is deemed professional and receive the pro firmware; under the bar, it's a desktop drive.
This may be true in some circumstances, however I have observed that enterprise drives from some vendors have a larger heatsink volume than the consumer drives, and also weigh a little more.
Possibly; however Seagate Barracuda 7200.11 and ES2, and Constellation 1 and 2 TB; Hitachi Deskstar and Ultrastar 1, 2 TB, and Western Digital Caviar Green 2 TB desktop and pro are all physically exactly identical.
Of course not. I've built several petabytes worth of storage systems in the past 15 years, OTOH.
> Using desktop drives, when 24 are mounted in a single chassis, the vibration from those drives will cause a higher rate of failure.
Absolutely. However this is not always directly applicable to all desktop drives. In fact I'm going to reveal a secret : physically, desktop SATA drives are exactly the same as professional grade 24/24h operation-guaranteed SATA drives. When they fall off the assembly line, they're tested for reliability and performance. Over a certain threshold, a drive is deemed professional and receive the pro firmware; under the bar, it's a desktop drive.
What is the most important difference between the desktop vs pro firmware? The desktop drive is supposed to be used alone. In case of an error, it will retry, retry and retry again endlessly to ecc-correct the error. OTOH, the pro drives "knows" it's part of a RAID array; at the slightest fault, it will simply cry "I'm failed" and give up. So in case of a transient error, your IOs won't be blocked.
There are some other differences depending upon the maker: for instance all Hitachi GST drives carry an accelerometer, but the desktop drive firmware don't know how to use it to compensate for low-frequency vibrations.
WD desktop drives have particular settings that make them extremely dangerous to use in RAID arrays.
Note that the "pro/consumer" threshold can be moved to reach some volume threshold regardless of the actual drive quality. This happened, I've been bitten.
Anyway, prefer the pro drives even if there 50% more expensive. It will save you some headaches.
> When a single drive in your 24 drive chassis fails, how do you know which one it is?
First, I suppose the maker (in my case, my team), carefully checked that all drives are properly labeled (so that drive 1 is labeled 1, etc); second, decent RAID controllers can flash a drive LED (Adaptec 5xx5 or 6xx5 series come to mind).
> Can you handle a double disk failure without losing data?
With drives of 1 TB or more, RAID-5 is definitely out and has been so for several years. RAID-6, RAID-6, RAID-6 is the way to go.
> These are things that enterprise storage vendors spend months with engineers designing.
E-xact-ly. BTW I'm an enterprise storage vendor. However I'm really too far from Louisville to be able to ship there and support it. I just mentioned what is possible; don't forget that nowadays, when you're buying an SGI (or many other big names) storage system you're buying Supermicro hardware.