Plenty of 2.5" JBODS, here’s one example, and they are cheap.
That’s interesting, do you have a reference ? I didn’t know those existed.
It is not worth checking.
- TB density is half of 3.5" drives (i.e., 2x 2.5" slots = 1x 3.5" slot) - for 20 TB 3.5" vs. 5 TB 2.5"
- HD power consumption is about the same (4x 5TB 2.5" = 1x 20 TB 3.5")
- 2.5" JBODs power consumption is 2x of 3.5" JBODs (due to #1, one needs 2x 2.5 JBODs)
- 2.5" warranty is usually only 2 years, life span is usually shorter
- the only potentially good thing is that the airflow for 2.5" is better, thus one can make those JBODs kind of quiet (run fans at about 6-10%)
The SC417 series, plus a few others:
iT’S nOt WoRtH CheCKiNg
Nearly all your points are guesstimates and not real-world actualities.
Thankfully I am done with this place as I now have a buyer. Take care.
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I have Dell sc200 JBODs, and those are virtually identical to sc220 (what is the same as your md1220). Enclosures are externally identical, MCUs are identical (different F/W, but one can reflash sc200 to sc220 and vice versa). PSUs are exactly the same. The difference is only in the backplanes (12x vs 24) and of course caddies.
As mentioned above, I used Seagate 20TB 3.5" ST2000NM007d (https://www.seagate.com/content/dam/seagate/migrated-assets/www-content/datasheets/pdfs/exos-x20-channel-DS2080-2111US-en_US.pdf). Based on that:
1.a. sc200 takes 12x 3.5", giving 240 TB
1.b. sc220 takes 24x 2.5", giving 120 TB
So, this one is check
Using provided docs
2.a. 1x 20 TB draws ~9.4 W
2.b. 1x 5 TB draw 2.1 W, giving 8.4 W equivalent (RW is listed as 2.1, but then they added 1.9 W average without explaining how they count it, so I would rather use 2.1)
So, this one is also check
This is just JBOD’s power draw (sans HDs). sc200 with 2x PSU, 2x MCU draws ~60 W at default fan speeds (I have measured it at wall). You need 2x sc200 to get the same TB as sc200, thus JBODs power draw is exactly 2x for sc220.
Another check
Actually, what it means is that based on #2 we have an extra 1 W per 1x 3.5" drive / 12 W per JBOD. Thus, the extra JBOD for 2.5" drawing ~60W will draw about 48 W extra what could be used to power ~5x 3.5" drives
Based on those data sheets:
4.1. 20 TB drive - 5 years
4.2. 5 TB drive - 2 years
Actually, for 20 TB, they also provide MTBF, but don’t do that for 4 TB as it sucks. Also, nonrecoverable error rate is 10x higher for 2.5" drives
We have another check
I do control fans speeds and try to keep my drives at 39C. Those HDs are rather tall, leaving really not that much space for airflow, so HD temps are really sensitive to ambient temp. Given that 5 TB is 15mm tall, and 20 TB is 25 mm, the frontal HD area (width x height x HD_COUNT(12 or 24), the sc220 is 2,340 mm2, and sc200 is 2,700, thus way more room for good airflow in sc200.
So, this one is the last check.
Yeah, it hurts when one must write some BS like that not being able to point to even 1 item that potentially could be wrong.
All the better for this forum.
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Interesting but yes the density is lower, I wouldn’t buy it at that price, maybe lower as an experiment. I think you’re better off selling them as externals than for Chia mining.
Don’t take it personally. We’re giving you feedback based on our usage. I think if you’re not farming with them, you might also agree with our points, or you might know something we don’t. Either way, it’s a forum, not an ads site 
So you can expect some discussion about your offer.
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