On Fri, 18 Jun 2021 at 14:10, Patrick O'Callaghan pocallaghan@gmail.com wrote:
On Fri, 2021-06-18 at 09:02 -0300, George N. White III wrote:
On Fri, 18 Jun 2021 at 06:50, Patrick O'Callaghan pocallaghan@gmail.com wrote:
On Fri, 2021-06-18 at 08:58 +1000, Cameron Simpson wrote:
On 17Jun2021 12:15, Patrick O'Callaghan pocallaghan@gmail.com wrote:
On Thu, 2021-06-17 at 07:20 -0300, George N. White III wrote:
> The technical specifications of the drives should mention > startup power management. There may also be some power management in the dock. I've noticed that it is becoming more difficult to find detailed documentation of add-on hardware. At one time you could open the box, identify key IC's and get the spec. sheets, but now you may find a general- purpose CPU.
It's a cheap dock so probably not easy to find any technical documentation. One thing I might try is to swap the two drives around just to see if it's always the same one that causes the delay.
On the subject of power as raised by George, I had trouble with too many USB bus powered drives on the home server. A powered USB 3.1 hub helps me out there. Doubtless it has its own limits.
The dock has its own power supply.
Is this a full-featured dock with USB and monitor outlets or a disk only dock?
It might be useful to compare the rating of the power supply with the peak load from the drive spec sheet. Older high RPM drives had quite high startup draw. Does the power supply have multiple voltages or just one voltage (the latter requires conversion in the hub)? If the power supply can't meet the startup requirements of two drives then it must be doing some power management. The simplest approach would be to provide a delay before starting one of the drives.
Interesting idea. Mine is this model:
https://www.amazon.co.uk/gp/product/B06XYJGDTH/ref=ppx_yo_dt_b_search_asin_t...
The power block says its output is 3A at 12V.
The drives are both WD model WD10EZEX, (though the label on one says it has a 64MB cache and the other doesn't). Both labels say 5VDC, 0.68A and 12VDC, 0.55A. Looks like the dock's power should be enough.
The spec sheet < https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/pu...
says 12V peak load is 2.5 A. It does take power to spin up to 7500 RPM, and I doubt your supply could survive without staggered startup.
Amazon has a popular Sabrent disk-only dock -- one review notes:
Cons
- when using 2 drives and plugging or unplugging one drive BOTH
go offline, at least temporarily. NOTE: Seems to be a common limitation to all these docks. I have yet to find one that does not behave this way. Must be the way the SATA bus controller is designed.
- when plugging in 2 drives, they mount sequentially, meaning you
have to wait for one to mount before the other will
My problem is that one drive comes up almost instantly and the other takes 30 seconds. In fact I can live with that. My real gripe is that the kernel makes me wait even though the drive is not being accessed. If it just wants to make the drive available, it should be able to wait asynchronously.
Agreed, but then you need a way to tell the kernel that it won't need anything from the external drives so it is OK to continue booting. Have you considered automounting the drives?