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0 pointsstorus6mo ago0 comments

HDPlex GaN power supply?

1 HDD consumes around 5-7W idle, so with 8 HDDs you get to 40-60W on HDDs alone (all idle); adding 6W with N100 seems like insignificant fraction. The moment you actually use any HDD the consumption per HDD shots up to 8-10W whereas N100 shots up to 14W so you end up with 64-80W from HDDs and 14W from N100. Why would you like to squeeze component that is the least important (CPU) while retaining lots of SATA HDDs as that's your priority? Optimizing the wrong thing? If you wanted to lower power, the easiest way is to replace HDDs with 16TB SATA SSDs, each consuming 0.08-2W. Then CPU might be a bottleneck.

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M95D6mo ago

There is power management for HDDs, you know...

For my typical usage, the hard drives are probably more than 80% in sleep mode. If I had more SATA ports, I could probably add a frequent-access cache on a SSD and then they would be 99% sleeping.

The drives I have, ST2000DL003, consume 0.5W in sleep, according to the spec sheet. So all 8 of them would consume ~4W.

SirMaster6mo ago

If you care that much about power why are you using 8 tiny 2TB HDDs instead of 1 or 2 big HDDs?

You don't need a NAS for 16TB, you just need a RasPi with a 16TB USB HDD connected to it and a second one for backups that you keep mostly offline.

nine_k6mo ago

In a RAID6 with 8 drives, you can allow one disk to go offline and remain able to write, or two disks offline and remain able to still read 100% of data. You lose 2 of 8 = 25% capacity on redundancy.

With a mirror of 2 disks, if one disk dies, you can still read; if two disks die, you're toast. And you lose 1 of 2 = 50% of capacity on redundancy.

A quite different balance.

M95D6mo ago

Because TCO is less with these cheap old drives and I can have RAID5 instead of just RAID1 or no RAID at all.

But you're right. In a few years it will become advantageous to switch to a couple of larger HDDs. I could probably do it right now, but I don't yet trust these new drives as much as I trust the old ones, especially since the refurbished scandal.

j / k navigate · click thread line to collapse

0 pointsstorus6mo ago0 comments

HDPlex GaN power supply?

0 comments

M95D6mo ago

There is power management for HDDs, you know...

For my typical usage, the hard drives are probably more than 80% in sleep mode. If I had more SATA ports, I could probably add a frequent-access cache on a SSD and then they would be 99% sleeping.

The drives I have, ST2000DL003, consume 0.5W in sleep, according to the spec sheet. So all 8 of them would consume ~4W.

SirMaster6mo ago

If you care that much about power why are you using 8 tiny 2TB HDDs instead of 1 or 2 big HDDs?

You don't need a NAS for 16TB, you just need a RasPi with a 16TB USB HDD connected to it and a second one for backups that you keep mostly offline.

nine_k6mo ago

With a mirror of 2 disks, if one disk dies, you can still read; if two disks die, you're toast. And you lose 1 of 2 = 50% of capacity on redundancy.

A quite different balance.

M95D6mo ago

Because TCO is less with these cheap old drives and I can have RAID5 instead of just RAID1 or no RAID at all.

j / k navigate · click thread line to collapse