SAS/Enterprise not "Top Picks FreeNAS Hard Drives"?

[OneOfMany07]

I was looking at this page and was surprised not to see SAS drives in the list:
Top Picks for FreeNAS Hard Drives

Yes, 7200 rpm drives will generate more heat, but I'm surprised that for ZFS the reliability improvements that SAS drives seem to include aren't important if ECC RAM is so important.

Or is this site's info not relevant anymore with the mention of size of RAID vs the error rates we're likely to see? SAS vs. SATA - EnterpriseStorageForum.com

I'm looking at setting up a NAS of some sort, not settled yet on ZFS or BTRFS based, but was thinking about getting an SAS card + drives for the better reliability. The higher MTBF, lower error rates (including on the signaling side from SAS), and at least one drive doesn't seem crazy expensive to me...

For around $170-200 each on newegg (think one is 4kn and another 512n)
Seagate Constellation ES.3 ST4000NM0023 4TB 7200 RPM 128MB Cache SAS 6Gb/s 3.5" Enterprise Internal Hard Drive Bare Drive - Newegg.com
Seagate Constellation ES.3 ST4000NM0033 4 TB 3.5" Internal Hard Drive-Newegg.com

Yes, I've heard terrible things about some Seagate drives, but the alternatives seem much more expensive and might even have less hardware (like a WD Re 4TB SAS drive with 32MB of cache for $250). And I'd rather pay more now than buy another drive and need to deal with failures later, possibly after losing all my data.

If I planned on a case with hotswap bays I might be a little more willing to risk it, but I couldn't find anything "great" there. Mostly stories of loud cases, and some that might be killing drives with their heat (Silverstone DS380). There was an interesting option at u-nas.com, but it needs a 1u power supply and I'd rather use a standard ATX form factor (likely a quiet, efficient option).

Other than cost being a deterrent, if I'm planning to keep my drives well ventilated I think the higher RPM and reliability features should be worth it.

 

[Terry Kennedy]

Yes, 7200 rpm drives will generate more heat, but I'm surprised that for ZFS the reliability improvements that SAS drives seem to include aren't important if ECC RAM is so important.

Or is this site's info not relevant anymore with the mention of size of RAID vs the error rates we're likely to see? SAS vs. SATA - EnterpriseStorageForum.com

There's a bit of "apples and oranges" to that second article. A drive family that offers both SAS and SATA versions almost always has the same HDA and read/write channel (which is where those errors happen) on the SAS and SATA models. For example, the Hitachi He8 family (PDF) has the same 1 in 10^15 error rate on all models. Like the "1K is 1000, not 1024" HDD size issue, the one-in-N error rate is an industry standard and always shown that way. If the manufacturer's design testing shows that the actual error rate is 3 in 10^16, that's going to get rounded down to 1 in 10^15, even though it is a number about halfway between 1 in 10^15 and 1 in 10^16 (and actually closer to the second).

This is also a worst-case value. Actual performance will be much better. Just like memory, where people said "Megabytes instead of Kilobytes of memory? You'll get so many errors that the average uptime will only be minutes!". (Substitute GB/MB instead of MB/KB if you're a young-un.) Yet today people often have systems with 16GB, 32GB, or even more memory and no ECC.

A lot of the features of "Enterprise" drives (regardless of SAS / SATA) don't really get you a lot in the home or SMB environments. An enterprise drive is expected to sit in a chassis with a bunch of other enterprise drives and deal with both the vibration of its neighbors and the bouncing it gets when an adjacent system is pulled out of the rack for service. And because they are packed in there like sardines (like 60 drives in 4RU), they are exposed to higher temperatures than a few drives in a smaller chassis. Conversely, enterprise drives expect that they'll be spinning 24x7 and in a relatively constant temperature / humidity environment, which isn't usually the case in the home / SMB environment.

For around $170-200 each on newegg (think one is 4kn and another 512n)
Seagate Constellation ES.3 ST4000NM0023 4TB 7200 RPM 128MB Cache SAS 6Gb/s 3.5" Enterprise Internal Hard Drive Bare Drive - Newegg.com
Seagate Constellation ES.3 ST4000NM0033 4 TB 3.5" Internal Hard Drive-Newegg.com

I haven't purchased drives from Newegg in years because of experiences with very poor packaging. They may have improved or they may not. HGST enterprise drives (not sure about their consumer models, but I think so) also record shock / drop info when the drive is not powered on, so you can get a warranty rejection for a drive you never mis-handled if the seller packed it badly. This is likely to become more common - one manufacturer (not HGST) told me "If we get a drive back for warranty replacement, even a no-problem-found one, we've lost money on that drive".

If I planned on a case with hotswap bays I might be a little more willing to risk it, but I couldn't find anything "great" there. Mostly stories of loud cases, and some that might be killing drives with their heat (Silverstone DS380). There was an interesting option at u-nas.com, but it needs a 1u power supply and I'd rather use a standard ATX form factor (likely a quiet, efficient option).

There just isn't a market for silent cases with lots of hot-swap bays. If there was, trust me - Supermicro and others would be building them. Some people here buy those cases anyway and then try to reduce the fan noise by changing fans, futzing with the fan speeds, etc. Personally, I don't see the point.