Hard Drives Made for RAID Use

An anonymous reader writes "Hard drive giant Western Digital recently released a very interesting product, hard drives designed to work in a RAID. The Caviar RE SATA 320 GB is an enterprise level drive without native command queueing and uses an SATA interface. In works better in RAID than other drives because of features like its time-limited error recovery and 32-bit CRC error checking, so it is an option when previously only SCSI drives would be considered."

Comments

Slashdot: Stories Made For Ad Use

[Anonymous Coward]

Sheesh, this is a VERY thinly disguised ad. Here's a direct link to NewEgg $169. Has the same details as this "story."

Re:Slashdot: Stories Made For Ad Use

[cperciva]

On the newegg link they list the MTBF as 1 million hours. Google tells me that that is about 114 years. How can it have such high mtbf?

MTBF is defined as [short time period] * [number of drives tested] / [number of drives which failed within that time period]. An MTBF of 114 years doesn't mean that half of the drives will survive for 114 years without a failure; it means that if you run 114 drives for a year, you should expect to have 1 failure.

A more intuitive way of conveying the same information is to say that the drives have an expected failure rate of no more than 1E-6 per hour.

Re:Slashdot: Stories Made For Ad Use

[Rasta Prefect]

On the newegg link they list the MTBF as 1 million hours. Google tells me that that is about 114 years. How can it have such high mtbf? Is that newegg just not having correct data or is there something special about these drives (or are they designed to be "used" less)?

Easy: You, like most people, don't know what MTBF means. MTBF is only meaningful in context with the expected lifespan of the device. This is probably somewhere in the neighborhood of 5 years, or about 43,800 hours. Essentially, what the manufacturer is saying is "Based on some data, we estimate that if you run x number of these drives, the average time between failures will be 1,000,000/x hours, up until the expected lifespan of the drive, at which point all bets are off"

For computer hardware this is always some sort of extrapolated estimate, since they have of course not actually been testing the drive for it's expected lifespan, or it would be obsolete by the time they released it.

Re:Slashdot: Stories Made For Ad Use

[whoever57]

An MTBF of 114 years doesn't mean that half of the drives will survive for 114 years without a failure; it means that if you run 114 drives for a year, you should expect to have 1 failure.

That is a good explanation. Many people confuse MTBF with lifetime.

Most products (and especially electronics) have a failure rate that when plotted over time looks like a bathtub. There is a high initial failure rate (infant mortality) that drops over time to a base rate (the random failure rate described by MTBF), this low failure rate continues until one reaches the end of useful life of the product, when the failure rate rises once again as age and wear effects cause the device to fail.

Note that most extended warranties are designed by the seller to kick in after the early failure rate has droped, but expire before the end-of-life failures.

About time

[Tuor]

While I've been a proponent of SCSI for a long time -- Apple really was thinking ahead when it had it in Macs all those years -- it has been getting thread-worn. Ultra-wide-tall-double-hex-SCSI is just getting to be too much!

SATA is the right technology, especially for controllers since each channel is dedicated. The only alternative is Firewire, and there are no native controller drives.

Sal Cangeloso is a moron

[laing]

The manufacturer specifically says to only use these in a RAID-1 configuration (mirroring). They have a reason for this: The error recovery mechanisim is abbreviated. So what does Sal do... He connects two drives in a RAID-0 configuration. Now his data reliability has gone to about 1/4 of a regular drive.

Re:earth to 11 year old kid

[alc6379]

Mod me offtopic, or whatever, but this has to be the most dumb-ass review I've ever read. It's a drive meant for RAID use, as in RAID 5 or RAID 1, in servers, where data integrity is very important. But what does this guy do?

...he puts it through the paces of a desktop hard drive. Where's the test of how it could run under mySQL? It's been replaced by a comment about how you can never have too much space "in this age of DVD-burning, file-sharing, and 40 GB MP3 players." Who the fuck cares about that on a server?

Where's the review of how well it facilitates serving pages through Apache? Oh, that's replaced by "Look how neat the drive looks!"

...Nope. This FA was a waste of time, not just for the reader, but for the author, and for Western Digital to have even sent the drives to this guy. He should go back to playing UT2k4OMFGBF2, and find someone who actually knows something about industry usage patterns on hard drives like this to write a thoughful review.