[lug] USB3 vs eSATA III question

[Lee Woodworth]

I have generally not had trouble booting usb disks with an initrd. External
USB2/3 or sata->USB2/3 enclosures using LVM. It helps to have root=/dev/mapper/....
on the kernel command line, and similar in fstab.

Bios support for gpt partition tables can be a factor for boot disks.
PC Engines APU2 systems detect usb3 external drives, but seabios segfaults
when it encounters a gpt partition table.

AFAIK, pcie m2 ssds can use either SATA or NVMe protocols (M or B keyed I think).
Do older bios versions know about NVMe? We have a Jan 2017 system where the PCI
controller for NVMe shows up as /dev/nvme0 (but not in /sys/class/block) while the 
connected m2 2280 shows as /dev/nvme0n1 and is an unbootable block device.
/dev/sda is a different m2 2280 using sata and is bootable (motherboard connector).

On 07/22/2018 05:20 PM, Bear Giles wrote:
> I have a couple NUCs with that type of drive, plus an NVMe on main desktop.
> No problems on any of them.
> 
> I just bought several of these:
> https://www.amazon.com/Lexar-JumpDrive-64GB-Flash-Drive/dp/B00S5V5PEC  I
> think I forgot to convert units - reading at 150 MBps is about 1.2 Gbps.
> Not as fast as that stick but it's a lot cheaper.
> 
> I'll be able to say something about booting from USB soon - one of my
> projects before I leave for trip next weekend is installing Ubuntu onto an
> external (USB) drive. I've been traveling with two laptops - a bit of a
> pain - and decided to try booting from a USB drive instead. My original
> thought was a USB stick but I might use a portable drive instead.
> 
> On Sun, Jul 22, 2018 at 4:58 PM, Orion Poplawski <orion at nwra.com> wrote:
> 
>> We have several PCIe sssd laptops running EL7 with no issues.  Great
>> performance.
>>
>>
>> On 07/22/2018 12:39 PM, Davide Del Vento wrote:
>>
>>> I don't know anything about your question, but I'm seeing the most
>>> recent/performant (SSD) drives are using PCIe instead of anything
>>> else. I've also heard that booting linux from PCIe can be troublesome,
>>> so I think I'll buy a normal SATA drive (I'm in the market for a small
>>> one).
>>>
>>> On Sun, Jul 22, 2018 at 12:27 PM, Bear Giles <bgiles at coyotesong.com>
>>> wrote:
>>>
>>>> This is mostly from curiousity...
>>>>
>>>> USB 3 has a claimed bandwidth of 3 Gbps.
>>>>
>>>> eSATA II has a claimed bandwidth of 3 Gbps, and eSATA III has a claimed
>>>> benefit of 6 Gbps.
>>>>
>>>> I don't think any USB stick is going to be pushing 3 Gbps (but I'm not
>>>> 100%
>>>> certain), but perhaps an external hard drive, esp. an external SSD. But
>>>> is
>>>> that actually realistic?
>>>>
>>>> In contrast my experience with eSATA is that it really is akin a
>>>> traditionally installed disk.
>>>>
>>>> Like I said this is mostly from curiosity. I noticed my recent systems
>>>> haven't had eSATA ports but it's easy to add a half-height card for one.
>>>> Ditto external drives - they usually only have USB 3 but if you buy an
>>>> external drive case for your own drive then it's easy to find them with
>>>> both
>>>> USB 3 and eSATA. So I have my eSATA gear but it might not be necessary
>>>> any
>>>> longer if the quoted USB 3 numbers are accurate.
>>>>
>>>> Does anyone else have experience with both USB 3 and eSATA?
>>>>
>>>> (Meanwhile I'm wondering what to do with a few old external drives that
>>>> are
>>>> USB 2. They're so much slower and smaller than my external USB 3 drives.)
>>>>
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>>>
>>
>> --
>> Orion Poplawski
>> Manager of NWRA Technical Systems          720-772-5637
>> NWRA, Boulder/CoRA Office             FAX: 303-415-9702
>> 3380 Mitchell Lane                       orion at nwra.com
>> Boulder, CO 80301                 https://www.nwra.com/
>>
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>>
> 
> 
> 
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