RAID 5 or 6 HDD Question...why are larger or smaller ones from some brands better?

[NickZac]

Okay...bear with me for putting it in this section as there is no section that fits perfectly and this relates to selection for HDDs for a RAID system that will be Macs-only. So for my RAID 1 system I've recently (as in the past couple of years) used the WD RE4, which as you likely know is a 7200RPM 3.5 inch enterprise class HDD. I've used the 500 GB models for a while and while they still have a few years of expected service life, I have another issue. Recently large media files have made it so that two 500 GB HDDs (well really 1 given it is mirrored) is not enough, and so I was going to go for the 2 GB WD RE4s in a RAID 5 or RAID 6 setup...so I went to buy them and noticed that unlike the 500 GB RE4, the 1TB+ RE4s have only so/so reviews. Then I noticed that most of larger WDs have inferior ratings to the smaller ones. Where as the sub 1TB 'Black' lines and enterprise lines are all the rave, the 1 TB and even more so the 2 TB models aren't reviewed nearly as well. Is this just coincidence or does this have to do with more wear from increased platters? I don't mind spending more on enterprise grade level but I only want to if I get enterprise class data protection.

 

[mdgm]

In the same generation of drives all higher capacity drives tend to be less reliable. Enterprise disks are more reliable than the consumer variants.

There are other brands too that you can look at like Hitachi, Samsung and SeaGate.

I'd go with RAID-6. But still backup your data. Data stored on a single device is not backed up. There are several problems that RAID as good as it is can't protect you against. RAID is a high-availability/redundancy solution not a backup.

 

[wonderspark]

I built an eight disk RAID in August of 2011 with 8x WD 2TB RE-4 disks. WD2003FYYS, all from either Amazon or Provantage, depending on who's price was best at the time, as I bought them in batches as I had the funds. I've had three of them since June or July of 2011, and the whole set of them have been in use for 12+ hours a day, 6+ days a week.

When I finally got all eight in August, I built a RAID3. That was good, but it took too long to build (40 hours), and I decided to test out a RAID6 which turned out to be superior to all other setups for me. These disks have made me extremely happy. The RAID6 initialized in under 5 hours.

All eight in RAID0 gives 1101MB/second on my AJA System Test on a 16GB test with cache off. The drives are individually rated at 138MB/sec max, and if you do the math, 8x138=1104. The fact that they ran collectively at 137.625MB/sec means they're all working at top speed.

All eight in RAID6 gives 816Mb/sec write, 714MB/sec read in the same test. I pulled one disk and tested again, and got 487MB/sec write, 191MB/sec read with cache off, and 482MB/sec write, 3535MB/sec read with cache on. That's while it was rebuilding the RAID when I re-inserted the pulled disk. I was able to continue editing DSLR 1080p video as it was rebuilding, which only took 5 hours and some minutes.

I have this data backed up on separate individual disks, and I agree that even with 2-disk fault tolerance, it's no excuse for not backing up, if you care about the data. I happen to have a lot of disks, so this isn't a problem.

tl;dr = Western Digital's 2TB RE-4 disks are awesome, and I see no reason not to trust them.

 

[FireWire2]

RE vs desktop

Okay...bear with me for putting it in this section....

My conspiracy theory that HDD manufacture just want to milk business, therefore they made a RE drives... All it is just enable the TLER, so it wont go MIA on you while it runs as a RAID member. (RAID engine don't like drive goes missing)

To proved my point I'd build a 180W 40TB NAS/iSCSI server with ALL GREEN drive, 20x of them; run 24/7. It runs over two years with 2 HDD had been replaced.

On other hand I would use the Hitachi Drive Desk star for DAS device

 

[joaoferro37]

My conspiracy theory that HDD manufacture just want to milk business, therefore they made a RE drives... All it is just enable the TLER, so it wont go MIA on you while it runs as a RAID member. (RAID engine don't like drive goes missing)

To proved my point I'd build a 180W 40TB NAS/iSCSI server with ALL GREEN drive, 20x of them; run 24/7. It runs over two years with 2 HDD had been replaced.

On other hand I would use the Hitachi Drive Desk star for DAS device

What about vibration tolerance, calibration?
24/7 running but how about data rate and IOs?
DIY NAS RAID is good for BT download but never for business.

 

[kwikdeth]

I built an eight disk RAID in August of 2011 with 8x WD 2TB RE-4 disks. WD2003FYYS, all from either Amazon or Provantage, depending on who's price was best at the time, as I bought them in batches as I had the funds. I've had three of them since June or July of 2011, and the whole set of them have been in use for 12+ hours a day, 6+ days a week.

When I finally got all eight in August, I built a RAID3. That was good, but it took too long to build (40 hours), and I decided to test out a RAID6 which turned out to be superior to all other setups for me. These disks have made me extremely happy. The RAID6 initialized in under 5 hours.

All eight in RAID0 gives 1101MB/second on my AJA System Test on a 16GB test with cache off. The drives are individually rated at 138MB/sec max, and if you do the math, 8x138=1104. The fact that they ran collectively at 137.625MB/sec means they're all working at top speed.

All eight in RAID6 gives 816Mb/sec write, 714MB/sec read in the same test. I pulled one disk and tested again, and got 487MB/sec write, 191MB/sec read with cache off, and 482MB/sec write, 3535MB/sec read with cache on. That's while it was rebuilding the RAID when I re-inserted the pulled disk. I was able to continue editing DSLR 1080p video as it was rebuilding, which only took 5 hours and some minutes.

I have this data backed up on separate individual disks, and I agree that even with 2-disk fault tolerance, it's no excuse for not backing up, if you care about the data. I happen to have a lot of disks, so this isn't a problem.

tl;dr = Western Digital's 2TB RE-4 disks are awesome, and I see no reason not to trust them.

[edit] nevermind, didnt notice your RAID card was listed in your signature.

 

[FireWire2]

What about vibration tolerance, calibration?
24/7 running but how about data rate and IOs?
DIY NAS RAID is good for BT download but never for business.

Sorry! Been buzy lately with FC dual 8Gb/s NET.Edit SAN.

Are you kidding, right?

I have freeNAS as FileServer in my company for 2yr+ without a single hiccup. A single Gb NIC serves 20+ nodes

and has iSCSI base on openfiler that transfer over 200MB/sec (team NICs)

It is how you manage it... As you can see there are so many posts from commercial NAS that gives user problem