USB > SATA docking >16TB?

[Ed.Kloonk]

Ed's got a really big disk.

Drive docks on eBay seem to max out specs at 16TB. Cannot find anything that exceeds this limit. Only have USB3/A ports on Linux laptop.

What are the kool kidz using to read the newer drives?

[Someone]

Isn't that just marketing nonsense from the end manufacturers of the enclosures? LBA48 should leave any size limits well off into the future yes?

USB should be backwards/forwards compatible so a recent 3.1 or 3.2 bridge chip should work just fine.

[Ed.Kloonk]

Isn't that just marketing nonsense from the end manufacturers of the enclosures? LBA48 should leave any size limits well off into the future yes?

USB should be backwards/forwards compatible so a recent 3.1 or 3.2 bridge chip should work just fine.

Don't know. Just want something that will last a few years before becoming another shelf ornament.

[Someone]

Isn't that just marketing nonsense from the end manufacturers of the enclosures? LBA48 should leave any size limits well off into the future yes?

USB should be backwards/forwards compatible so a recent 3.1 or 3.2 bridge chip should work just fine.

Don't know. Just want something that will last a few years before becoming another shelf ornament.

So buy a prepackaged drive in an enclosure that the manufacturer has assembled for you? Then it is not on you to figure out any (confusing) compatibility issues.

[David Hess]

As far as I know that limitation is just because they have nothing larger to test with, and the SATA to USB bridge will handle higher capacities just fine.

Personally I am looking for a more portable redundant high capacity storage solution, but that will probably end up being me building my own smaller NAS box.

[Doctorandus_P]

Browsing though some store I find 18TB, 20TB and even 22TB too.

In the past there have historically been some 5 to 10 hard limits to maximum size. I think some were bios related and other with max number of sectors overflow in drivers. both on the old IDE and later on SATA. Small credit card sized Linux computes sometimes have a limit at 2TB via SATA, but I never looked into why that is.

The idiots who devise uSD card standard also seem to update the standard with size increments of a factor or 4 or so.

As far as I know the designers of the USB Storage Device Class looked further ahead. There still may be some limit, but I don't know where it is.

[pcprogrammer]

Slightly off topic, but aren't these big hard drives slow when writing lots of data and therefore not so good for making backups.

A while back I wanted a small form factor external drive with only 4TB and bought a seagate one on amazon. When it arrived I stared to backup my main disk and at first it was quick, but the speed went down real fast and it would have taken a couple of days to make the backup. Turns out the drive uses shingled magnetic recording (SMR) instead of conventional magnetic recording (CMR)

So whenever I look for a new drive to buy I make sure it uses CMR.

[Doctorandus_P]

I had a short peek trough a listing of a big PC shop which has listed around 200 different HDD's on their site and bigger HDD's tend to be quicker. A lot of them are somewhere between 160MB/s and 230MB/s, while the 18+GB disks quite often go between 250MB/s and 280GM/s (All are read speeds.

I've seen 18GB disks with "CMR" and another one I looked as was the
WD Gold, 18 TB, WD181KRYZ, and it uses "EAMR" (Energy Assisted Magnetic Recording) and they claim a read speed of 269MB/s
WD Red Pro, 22 TB WD221KFGX, SATA 600, 24/7, AF claims to use CMR and also  268 MB/s.

I only spent about 5 minutes on this, but your claim does not seem to hold.
And there are also plenty of backup applications where speed is not of great concern. They start the backup in the evening, and as long as it's finished the next morning it's all right.

[Ed.Kloonk]

Yeah. Avoid SMR. It is cancer.

As for the speed slowing, a very long time ago I found that slowing was caused by a bad usb extender cable. Removed the cable and all good.
Look in the logs, any mischief should be showing up there.

[David Hess]

Slightly off topic, but aren't these big hard drives slow when writing lots of data and therefore not so good for making backups.

I have several Crucial MX500 2TB drives now that are used in pairs for offline backup and large continuous transfers can slow down to about 100 MB/s because of heating.

[pcprogrammer]

100MB/s is still high speed. The drive I bought and tried it with went down to ~2MB/s. It was crap.

I only spent about 5 minutes on this, but your claim does not seem to hold.
And there are also plenty of backup applications where speed is not of great concern. They start the backup in the evening, and as long as it's finished the next morning it's all right.

It was no claim but a question. For a business sure backup is done overnight, but as a retired home user I just want to backup my full system once in a while, and want it to be quick and cheap.

Sure there are big disks that use CMR, but they also have a big price. The cheaper ones mostly use SMR.

Plus you have to make sure to look for CMR and they don't always list this information on the cheaper external hard drives.

The read speed is not the concern. It is the sustained write speed that matters.

[David Hess]

100MB/s is still high speed. The drive I bought and tried it with went down to ~2MB/s. It was crap.

But it can remove the speed advantage of SSDs over hard drives in some applications.  My SSDs will reliably write at 400MB/s and higher over shorter durations, but long backup sessions settle at about 100MB/s.

[Berni]

The USB to SATA devices are hit and miss with large drives. I seen some that have issues with >2TB drives. It would detect the drive just fine and show up, but it just reads garbage from it. The limits for SATA are pretty huge so they shouldn't be a problem. I am guessing the problem is actually in the firmware of these things.

As for SMR drives. They work fine when only partially full, it is when they are filled up all the way the write speed slows down to single digits. Just like on SSDs these drives use TRIM to tell the drive what parts are empty, so it arranges data in a way that writing occurs in areas that overlap the empty areas. But when the drive gets full (like >90%) these areas are not available anymore so the drive has to constantly shift and rewrite data because it is destroying it by writes overlapping the areas that already store data.

So for backup use SMR drives can be fine, especially if you have a system that does incremental backups by adding on extra archive files rather than rewriting the whole thing. If the performance drop is an issue you can shrink the filesystem partition by 10% to make sure a small part of the drive is left empty.

But yeah better to just stick to CMR drives and be careful that you don't accidentally buy a SMR drive as they often don't tell you about it. I ended up with a SMR drive by accident before because i was using WD Red drives and liked them, sensibly none of the WD Red drives had SMR so i bought a WD Red drive once again. Only to find out that the idiotic bastards at WD have secretly switched to SMR at one point, keeping the WD Red name while selling the proper CMR drives as WD Red Pro. 

[SiliconWizard]

My disk is bigger than yours anyway.

[Halcyon]

Ed's got a really big disk.

I see what you did there. ;-) You should see my deck. It's quite the sight as well.

[Ed.Kloonk]

Ed's got a really big disk.

I see what you did there. ;-) You should see my deck. It's quite the sight as well.

I expected better from you. Missed opportunity regarding the 'docking'.

 

[David Hess]

Just yesterday I was thinking of building another 2TB external USB drive from a Crucial MX500, but decided to look for alternatives.  Seagate seems to be the last 2.5" hard drive maker, at least above 2TB, but all of their drives are SMR, and since the larger capacity ones are 15mm thick, they will not fit in the external enclosures that I prefer.