From: blockedofcourse@foo.invalid
On 12/12/2025 12:14 PM, Sergey Kubushyn wrote:
> Don Y wrote:
>>>>> The opposite is possible -- SATA drive can be plugged into SAS
receptacle so
>>>>> those are SAS/SATA physical connectors.
>>>>
>>>> All of my backplanes are SAS/SATA (though not mix and match). So, I
don't see
>>>> the value of keeping any of the SATA (only!) sleds. I can, of course,
use them
>>>> in the existing backplanes but see no advantage to keeping them over an
>>>> equal number of the SAS/SATA sleds.
>>>
>>> Yep, there is no reason unless you have SATA-only device and a box of SAS
>>> drives that you might accidentally plug in there :)
>>
>> But, as I can affix SAS drives to the SAS/SATA sleds, wouldn't the sleds
>> be accepted by a SATA-only backplane? Or, am I interpreting this from the
>> wrong point of view?
>
> Nope, they won't be accepted. The SAS/SATA sled has SAS connector and
> SATA-only backplane has that protrusion that is going into the slot in a
> SATA connector. That protrusion will not let a SAS/SATA sled to be plugged
> in because of that protrusion and no slot for it in the connector.
Sorry, I wasn't explicit enough.
I know the DRIVE will create interference. But, if the assumption is
that you want different sleds so the SLEDS tackle the interference
(to protect the connector(s) involved), then the SAS/SATA *sled*
won't interfere with the physical mating; it will rely on the
connectors to prevent the mis-mating.
> The SAS and SATA connectors are identical in all respects except that slot
> that is only present on SATA plug.
And the extra conductors on top of it.
>> I.e., the mounting holes for SAS and SATA drives are identically placed.
>> So, I can mount a SATA or SAS drive on a SATA sled or a SAS/SATA sled.
>> (there's nothing preventing the SAS from being mounted on the SATA-only
>> sled).
>>
>> So, I *could* "force" that sled into a SATA-only backplane.
>
> There is no protection from a good sledgehammer blow, ya know...
If you were mating a free-floating SATA cable to a drive, you
would perceive the interference. But, once you have a drive
on a sled guided by its slot, it's pretty easy to push too hard.
[I've a friend who managed to mate a 4 pin power connector on
an IDE drive "backwards". I wouldn't have thought it physically
possible due to the mass of those connectors!]
>> I.e., the better solution would have been for the drives to have different
>> mounting hole patterns so you could NOT mount a SAS drive on a SATA-only
>> sled and have the connectors trying to mate. As it stands currently,
>> the sleds require the person who affixes the drive to observe the
>> markings on the sled to avail himself of that protection. (?)
>
> You can plug a SATA drive into SAS/SATA backplane but not vise versa. Most
Yes, I understand that. I have (literally) scores of drives of both types
and I freely exchange them between machines (always careful to use ALL
SATA or ALL SAS).
But, my machines are intended to accept both types of drives. So,
whether I use a SATA sled in a SATA/SAS slot or a SAS/SATA sled
in a SAS/SATA slot, there is no problem.
I *don't* have a machine that is SATA only. Nor any sleds labeled
as SAS only. So, there are combinations that I can't try.
> (if not all, not sure) SAS controllers also support SATA drives so there is
> nothing wrong with plugging a SATA drive in a SAS backplane. On the other
> end, almost(?) none of SATA controllers support SAS so it might be a problem
> plugging a SAS drive into SATA-only backplane. This is why those have that
> protusion in the receptacle and slot in the plug. That makes plugging a SAS
> drive into such receptacle impossible.
>
> Making DIFFERENT connectors for SAS and SATA is a bad idea. SAS controller
> or backplane can work with SATA drives so it makes sense to have the
> connector IDENTICAL. If they had been different it would've been very
> awkward to make a SAS/SATA sleds/backplanes if possible at all.
I'm not advocating for a change in connectors but, rather, for keying
on a "SAS only" sled to ensure *it* can't mate with a SATA-only backplane.
If there were three types of sleds (there may well be but I only have
two different types) -- SAS, SATA, SAS/SATA -- then the SAS sleds would
not be physically compatible with the SATA-only cardcage/backplane.
As it stands (with SATA and SAS/SATA), you *should* be able to mechanically
mate a SAS drive mounted on a SAS/SATA sled with a SATA-only backplane
(barring interference from the connectors).
[If you were to rely on the *connectors* to ensure the correct drives
were mated, then you would have no need for different types of sleds!
So, the sled differences must have been introduced to differentiate
between drives *mechanically* without reliance on the connectors!]
The sleds have too many mounting holes and they are labeled unintuitively.
E.g., SAS and SATA drives mount using the exact same holes (the threaded
holes in the drives are in the same places). So, 4 holes to mount either
drive -- 2 on each side. Plus 4 more holes to mount 2.5" versions in
the same sleds. 4+4=8
This is a pic of all four combinations:
The two sleds on the left are "SATA" while those on the right are "SAS/SATAu".
The first (left) and third are SATA drives while the second and fourth (right)
are SAS drives.
Yet, there are *16* holes in each sled -- 6 on one side (where 4 should suffice
for 2.5 and 3.5) and 10 on the other (where 4 should suffice). Additionally,
the holes are independently marked for SAS vs SATA (whereas the same holes
should be used for each).
Here's a pic of the same drives/sleds but with the SAS/SATAu sleds mounted
using the holes marked "SATAu" (previously, were mounted with the "SAS" holes):
Note that interposers are not needed so I can't understand why the extra holes
and "mismarked" holes. If I mounted my SATA drives using the holes labeled
for SATA, the connectors wouldn't even come close to mating (by a large
fraction of an inch)! All I can assume is the sleds predate the SAS/SATA
backplanes (that don't require interposers) and haven't been updated to
remove those unnecessary mounting holes?
Here are pics of the mounting holes (both sides) for the SATA and SAS/SATAu
sleds, respectively:
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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