SCSI Hard Drive Life span

[mark burfitt]

Hi i am after a rough guide to how many service hours on average a HP SCSI 36.4gb 15k drive will run before failure

This is just a HP average would be great

[Uwe Zessin]

It sounds like you are after MTBF numbers. For a high performance SCSI drive it is measured in 10s of years these days, but such a number is not very helpful for an end-user, because nobody can tell when _a particular_ disk drive fails.

[Alzhy]

I still have a Sun workstation with the Motorola 68000 CPU -- it has 2 CDC WREN IV 400 Mbyte hardrives and still works.

Most 36.4 gb 15k drives are rated at about 1,000,000 hours MTBF. I'd say it depends mostly on temperature variations and how good the case/chassis containing the disk cools it.

[Cass Witkowski]

The 36GB 15K rpm disk used in the MSA1000 has several manufacturers. There is a NNNNNN-NNN number (e.g. 306641-002) on the drive listed below the model number that says it was manufactured by Fujitsu and has a MTBF (Mean Time Between Failure) of 1,200,000 hours.

â ¢MTBF = 1 / failure rate
â ¢Failure rate = 1 / MTBF
â ¢Failure rate = 1 / 1,200,000 hours
â ¢Annual failure rate = 1 / 1,200,000 hours * 8,760 hours per year
â ¢Annual failure rate = .0073

If I have 10 sites with 48 disks per site = 480 drives, I should expect 3.5 disk failures per year. 480 * .0073 = 3.5

Now the MTBF rating of 1,200,000 hours is almost 137 years. The drives are going to wear out long before this time. What is needed is the service life of the device or the MTTF (Mean Time To Failure) to determine when 50% of the devices will fail. This will give us how long the drives will experience the constant failure rate before they start failing out at the increasing â wear outâ failure rate.


The service life of this disk depends on the temperature of the Drive Enclosure (DE).
â ¢DE surface temperature 40Ë C (104Ë F) or less 5 years
â ¢DE surface temperature 41Ë C to 45Ë C (113Ë F) 4.5 years
â ¢DE surface temperature 46Ë C to 50Ë C (122Ë F)4 years
â ¢DE surface temperature 51Ë C to 55Ë C (131Ë F) 3.5 years
â ¢DE surface temperature 56Ë C to 60Ë C (140Ë F) 3 years

Even if disk is intermittently used the longest service life is 5 years.


For SATA drives the MTBF is around 600,000 hours and that is only with a 20% duty cycle. If you use the disk more than that the failure rates will go up. SCSI disks are design to be used with a 100% duty cycle.

Regards,

Cass