[kwlug-disc] Multi-bay docks ... 1 at a time??? [Was: Re: Linux-compatible eSATA expansion cards]

[unsolicited]

What caught your eye in the links that bears on the conversation at hand?

On 14-08-05 12:56 PM, John Johnson wrote:
> I have no opinion or experience to share but thought that the following
> links might be helpful.
>
> Ref: http://en.wikipedia.org/wiki/Chipset
> Ref: http://en.wikipedia.org/wiki/Northbridge_%28computing%29
> Ref: http://en.wikipedia.org/wiki/Southbridge_%28computing%29
>
> Note: According to one of the above, IDE, SATA & USB are on the
> Southbridge chip.
>
> JohnJ
>
> On 2014-08-05 12:07, unsolicited wrote:
>> On 14-06-30 09:53 PM, Khalid Baheyeldin wrote:
>>> On Mon, Jun 30, 2014 at 8:09 PM, Paul Nijjar <paul_nijjar at yahoo.ca>
>>> wrote:
>>>
>>>> In an ordinary situation, maybe. However, in this computer I am
>>>> planning to use all the internal SATA connections for other drives.
>>>>
>>>> Honestly the differences between eSATA and SATA still confuse me, even
>>>> after reading the Wikipedia article. Is it true that not all SATA
>>>> ports on a motherboard can be converted to eSATA with these
>>>> connectors?
>>>
>>> One important difference is hotpluggability.
>>> This depends on your chipset. There is a table here listing the
>>> supported
>>> chipsets.
>>>
>>> https://ata.wiki.kernel.org/index.php/SATA_hardware_features
>>>
>>> That page also lists PMP, if you want to attach more than one device
>>> to the
>>> same eSATA cable. Although, when I tried it with a dock that has 2
>>> drives,
>>> one drive would have normal speed and the other would be really
>>> slow.  ...
>>
>> Summary: Am I understanding the availability of possible solutions to
>> moving vms between computers (especially future laptops - single esata
>> port / USB 3 availability / no PMP controller) correctly?
>>
>>
>> Happened to poke and google around the web on this over the weekend.
>> Playing with vbox and wanting to move vms around my internal net -
>> leading to the need for GBs of extra space on both source and
>> destination. Over my net, ~35GB vm takes just over an hour to copy,
>> slow machines. Fast machine on one end about 1/2 hr. Same for machine
>> to external drive on USB 2 (to and from -> 1 hour). So happened to
>> poke about docks / what they and storage might cost. Idea of USB 3 /
>> SSD is attractive, but seems cost prohibitive. Also leads to the idea
>> of running the vm off external device, and schlepping to different
>> computers as needed. e.g. Hardware failure. Even if I don't have USB 3
>> & eSata on every machine today, presumably each new machine will at
>> least have USB 3.
>>
>> Given Khalid's note above that points out that dual-bay docks are
>> essentially pointless (more than 1 drive, slow on other drives), I
>> wondered why / what's up. Seems like whatever (multi-bay) such is
>> plugged in to must be -TO- a port multiplying sata controller or this
>> slow drive problem is run in to. Since PMP isn't required for a sata
>> controller, most everyone will be out of luck unless they know to
>> specifically search for such capability beforehand. (Making it seem
>> like multi-bay docks are are marketing ploy - most things you might
>> connect to can never take advantage of it?)
>>
>> Seems that only 1 drive can be talked to at a time (Command Queuing?)
>> / something PMP must be in the sequence to do the 'multiplexing'(since
>> any one drive can't saturate a SATA link unless it's an SSD) to try to
>> keep the link to the computer going full bore.
>>
>> Yet it does not seem that PMP is available at the device
>> (dock/adapter/drive) end - it has to be in the controller, and I
>> expect its unlikely for laptops to have them. Does this not:
>>
>> - render multi-bay docks pointless (unless a 'duplicator' or RAID)?
>>
>> - make simple adapters attractive e.g.
>> http://www.canadacomputers.com/product_info.php?cPath=95_96&item_id=35385P
>> more sensible - except still have problem of providing power to drive
>> if large capacity / 7200 RPM? (Let alone, not normally stocked?)
>>
>> - if eSata,
>> http://www.amazon.ca/eSATA-External-Bridge-Adapter-Converter/dp/B00DHCC7NQ/ref=sr_1_2
>> or
>> http://www.amazon.ca/Anker%C2%AE-Uspeed-Converter-Adapter-External/dp/B006J2L0ZM/
>> ?
>>
>> - render eSata useless vis a vis USB 3. i.e. New laptops will not
>> likely have multiple eSata ports - if any at all, but will likely have
>> multiple USB 3 ports (yet USB can do the multiplexing itself so no
>> need for PMP?)
>>
>> - make NAS / RAID-JBOD units make more sense as it will be managing
>> the (single) link to computer flow? Yet the point of adapters/docks is
>> quick disk flipping about, rather than digging into a (NAS) enclosure!
>>
>> - unless a laptop, live with digging into the case when moving drives
>> around. Back to advantage of cages, e.g.
>> http://www.icydock.com/goods.php?id=175
>>
>> So, it seems a single bay dock is the only thing that makes any sense,
>> and if multiple drives are needed, purchase multiple single bay docks.
>>
>> Yet I see 3TB limitations on drive sizes for such, and 6TB drives are
>> now here, with 8TB drives soon to come. I do see that
>> http://www.canadacomputers.com/product_info.php?cPath=14_679&item_id=047936
>> notes 'Up to 6.0 TB*', but it is not clear that that does not mean
>> MAX. 3TB PER BAY!
>>
>> I'm guessing this has more to do with the USB chipset in use only able
>> to understand MBR drives, not GPT.
>>
>> Seems like a net. NAS makes more and more sense, but schlepping GB of
>> images over the 2Gbps network vs local 6GBps sata III seems
>> counter-intuitive.
>>
>> Am I understanding the availability of possible solutions to moving
>> vms between computers (especially future laptops - single esata port /
>> USB 3 availability / no PMP controller) correctly?
>>
>>
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