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How long do disk drives last?

blog.backblaze.com

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Re: How long do disk drives last?

#101

Post by Sami_Lehtinen »

barrkel wrote: post #84
mikevm wrote: post #68

Earlier quoted context omitted.

The one thing to know about cheap consumer cloud backup solutions like CrashPlan and Backblaze is that they only have one copy of your data. So if their RAID array where your data is stored dies and cannot be rebuilt, it's all gone. You can Google for a few disaster stories about both companies.

Like I said, they are only one third of my backup strategy. My house burning down, or someone breaking in and going into my attic to steal my 30kg 4U server, should be the only two realistic scenarios in which I will need to rely on CrashPlan.

I do same, but in reverse. I use cloud servers, with versioning backups, but still beam additonal backups back to office. Just to survive total data center destruction disaster.

Re: How long do disk drives last?

#102

Post by pedrocr »

pedrocr wrote: post #100
jws wrote: post #58

Earlier quoted context omitted.

Greens have had problems with aggressive head parking. If you have an idle set of them you can go through their design limit of head parks in a couple of months and start to get failures shortly after. Done that. Check your S.M.A.R.T data. Look at the head park number. (Load cycles I think it is called, can't look it up now). If it is a six digit number, you are in trouble. For a server you want if to be in the same…

I assume you mean Start_Stop_Count. A quick check on two servers, each with 4 green drives in RAID6 and RAID5 setups tells me this hasn't been a problem. Both have Start_Stop_Count's below 100 (on the order of the number of boots the servers have had). I don't see any other number that could be the head park. The number I have been finding to be high is Hardware_ECC_Recovered (values between 1036555546 and 2699460003…

I may have spoke too soon. One of my servers has 2 Samsung Green and 2 WD Green drives in RAID6. Here's the SMART value that you seem to be discussing:

  $ for dev in `ls /dev/sd?`; do echo $dev; sudo smartctl -a $dev | grep Load_Cycle_Count; done | cut -d " " -f 2,40
  /dev/sda
  Load_Cycle_Count 24
  /dev/sdb
  Load_Cycle_Count 24
  /dev/sdc
  Load_Cycle_Count 1947798
  /dev/sdd
  Load_Cycle_Count 1907706
sda and sdb are the samsungs and sdc and sdd are the WDs. I also just replaced a failing Samsung Green drive in another machine with a WD and it already has a Load_Cycle_Count in the 10000s. I guess I need to start avoiding Green WDs at least, maybe the Greens altogether.

Re: How long do disk drives last?

#103

Post by dmourati »

baruch wrote: post #96
dmourati wrote: post #88

Ugh. Backblaze is one of those companies with an extraordinarily poor design that they flout and "open source" as if anyone would follow their lead. Take a look at the physical design of their system and combine that with the published data. Consider that to remove any harddrive from their setup requires physically removing a 4u rackmount storage pod from the rack. http://blog.backblaze.com/2011/07/20/petabytes-on-a-…

They do a different tradeoff here. There is no need for a hardware raid if performance is not your main concern (and even if it is hardware raid is no panacea), if they save everything to disk before acknowledging it they don't need a battery and I'm not sure what you refer to as cap. Their hardware design is specifically geared towards their use-case and I applaud them for knowing how to optimize for their use-case.…

cap=capacitor. http://www.lsi.com/downloads/Public/MegaRAID%20SAS/MegaRAID%...

Edited to add: They've optimized for hardware purchase price and given up reliability (HW RAID, battery, cap), performance, and maintainability. The strange thing is the overall cost of the storage system is driven by power, not purchase price. Smarter RAID controllers, like I link above, let you manage power by spinning down disks as they are unused and thereby reducing your power draw. Can't do that with SW RAID that I've ever seen. Take a look at Amazon Glacier which I suspect is using this power-off strategy to drastically reduce their costs.

Re: How long do disk drives last?

#104

Post by teach »

nisa wrote: post #83
jws wrote: post #58

Earlier quoted context omitted.

Greens have had problems with aggressive head parking. If you have an idle set of them you can go through their design limit of head parks in a couple of months and start to get failures shortly after. Done that. Check your S.M.A.R.T data. Look at the head park number. (Load cycles I think it is called, can't look it up now). If it is a six digit number, you are in trouble. For a server you want if to be in the same…

As someone who inherited 240 24/7 running WD-Greens: http://idle3-tools.sourceforge.net/ works fine but disabling the timer has negative performance impact. 3000 seconds is fine through. But you need a complete powercycle before the changes take effect. No more parking. Does make a difference in longevity in my not very scientific opinion. I can second the 200> bad blocks. Sometimes they still work fine after using b…

Good to know. I JUST bought a green WD drive (still in transit from Amazon) so my future thanks you.

Re: How long do disk drives last?

#105

Post by noonespecial »

rsync wrote: post #80
drzaiusapelord wrote: post #67

Sysadmin here. My experience: 1. Infant mortality. Drives fail after a couple months of use. 2. 3 year mark. This is where fails begin for typical work loads. 3. 4-6 year mark. This is when you can expect the drives that haven't failed earlier to fail. By this point, we're looking at 33% fail. Interesting that my experiences roughly match up with Chart 1. My experiences are 10 to 15k SAS drives. Slower moving 7200rpm…

Agreed RE: SSD drives ... It is very disappointing how flaky and unreliable SSD devices have been when their promise was just the opposite, due to lack of moving parts. Back in 1999/2000 I had a habit of building some personal as well as commercial servers in datacenters with compact flash parts (plain old consumer CF drives) as boot devices with the goal of fault tolerance in mind. There was a price to be paid in th…

I did exactly the same thing with CF. We had a default config that would operate read-only and leave the machine in a reachable state no matter what. Once we got that far, we'd mount some spinning rust or NFS and pivotroot and run a secondary init.

It was a huge win for uptime.

Re: How long do disk drives last?

#107

Post by mgraczyk »

Microsoft did a metaanalysis on general hardware failure based on the error reports sent by literally millions of consumer PCs. Although the results weren't particularly interesting (Hard drives fail the most, with rates consistent with what backblaze observed in the posted link), I was impressed by the sheer volume of data available to the study.

http://research.microsoft.com/pubs/144888/eurosys84-nighting...

Re: How long do disk drives last?

#108

Post by cenhyperion »

maratd wrote: post #9

It depends on the warranty period of the drive. Your hard drive manufacturer knows precisely how long the drive will last and sets their warranty period to expire right before your drive gives up the ghost.

> Your hard drive manufacturer knows precisely how long the drive will last

Care to back that up with any real data instead of baseless consumer speculation relying on time travel?

Re: How long do disk drives last?

#109

Post by fletchowns »

cenhyperion wrote: post #108
maratd wrote: post #9

It depends on the warranty period of the drive. Your hard drive manufacturer knows precisely how long the drive will last and sets their warranty period to expire right before your drive gives up the ghost.

> Your hard drive manufacturer knows precisely how long the drive will last Care to back that up with any real data instead of baseless consumer speculation relying on time travel?

They don't know exactly, but they have a very good idea. It's all based on statistics.

Re: How long do disk drives last?

#110

Post by brianwski »

dmourati wrote: post #88

Ugh. Backblaze is one of those companies with an extraordinarily poor design that they flout and "open source" as if anyone would follow their lead. Take a look at the physical design of their system and combine that with the published data. Consider that to remove any harddrive from their setup requires physically removing a 4u rackmount storage pod from the rack. http://blog.backblaze.com/2011/07/20/petabytes-on-a-…

Disclaimer: I work at Backblaze but I'm on the software side, I barely ever touch the storage pods anymore.

It is not true that the pod team must remove the 4U server from the rack. It is slid out like a drawer (no tools required, takes maybe 10 seconds). The drive or motherboard is then replaced, then you slide the drawer back in. So the 4U server must slide 18 inches one way, but zero cables have to be unplugged or replugged when done. This only takes one technician and no "server lift", the drawer supports all the weight.

I'm not defending this design, just correcting a mistake. Backblaze frankly "makes do" with this design because nobody will step up and make anything that fits our needs better. The number 1 criteria is total system cost over the lifetime of the system INCLUDING all the time spent on salaries of datacenter techs dealing with the pods. "raw I/O performance" is not that important for backup, so trying to sell us an awesome EMC or NetApp that costs 10x as much and has 10x the raw I/O performance is not very compelling to us. But if you came up with a design making it faster for our datacenter technicians to replace a drive faster while not significantly increasing overall costs in another area, we SURELY would listen.

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