Re: Seeking information on SATA hard drive hot-swapping . . .
- From: "Rod Speed" <rod.speed.aaa@xxxxxxxxx>
- Date: Mon, 24 Apr 2006 04:45:39 +1000
Stan Shankman <stantheman@xxxxxxxx> wrote
I have been reading around the internet, and trying to learn a few
things regarding SATA and hot-swapping.
This is what I want to do:
I want to permanently mount one SATA drive in my computer
(to be used as the boot and system drive). And then also,
I want to use one of those fancy drive sleds to plug and
unplug additional SATA drives (for data and backup use).
I would like to simply reach over and yank out the removable
drive any time I wish, and replace it with another drive.
That isnt a great idea, most obviously if
the system is currently writing to the drive.
(Now, if I have to go to the system tray, and tap on dismount or
something like that, so be it - I just want to know what I must do.)
Presumably you would also be happy to check that the drive
isnt currently being used before you physically remove it, say
with some sort of activity light etc.
Now, in researching this, I come up will all manner
of contradictory information - some people saying it
can't be done without special software etc. etc. etc.
Yes, its quite a mess currently.
But I am pretty sure that it can be done.
Yes it can.
I think the use of a controller that a supports
SATA hot-swapping is mandatory.
Correct.
Yet I do not have a good understanding of this
controller issue. - I wonder, could any SATA
controller support hot-swapping if it had a proper
driver? Or is there some hardware issue involved?
That isnt completely clear currently.
I don't know. One thing I have discovered is that controllers
are not well marketed insofar as hot-swapabilty is concerned.
Yeah, but thats also true of the basic question
about whether it supports non RAID configs too.
It is not clear whether a SATA controller specification
that claims "support for hot-swapping" is referring to
just a RAID or not.
Yep.
By the way, I do not wish to run a RAID. I do not yet know if a
controller that supports hot-swapped RAIDs is by implication also
able to support single dive hot-swapping. Is there a distinction?
Yes.
I don't know.
Oh, and you think that is bad? What about the motherboard based SATA
controllers. Just try to find out if yours supports SATA hot-swapping
or not. It's like pulling teeth trying to find out this information.
True of whether its designed to support non RAID too,
although thats becoming less true than it used to be.
Do all SATA drive sleds work with SATA II?
Nope.
If not, why not?
Some of them are very poor designs which dont even
fully support SATA, essentially because they flout the
SATA standard in some areas, essentially because
they appear to be crude kludges of ATA drive 'sleds'
Then there's the separate question of the power connector.
Quite a few drives have a molex connector, the old ATA
power connector, and that cannot be used for hot swapping.
What, for that matter, does a drive sled do?
Its mostly about the mechanical stuff, providing a decent
solid way of sliding the drive in and out of the system.
Why is it not just a convenient place
to house a couple of connectors?
Because there is more involved than just the connectors.
The mechanical arrangement needs to be convenient,
and many have some form of fan etc because those
configs dont get much airflow over the drive.
Or is, in fact, that all there is to it?
Nope.
I mean, is it possible to not use a drive sled at all? Can one
simply make the SATA cable and power cable accessible
and then manually plug and un-plug SATA drives?
Nope, because the standard requires simultaneous
insertion of two connectors if you're hot plugging.
I mean isn't that what the SATA hot-swap specification calls for?
Nope.
If not, what is the true definition of hot-plugging?
At that mechanical level, the simultaneous
insertion and removal of two connectors.
The short story is that you do need hot swap support in the drive,
the controller. And in the OS if you want to be able to reef the
'sled' out regardless of what the OS is doing with the drive,
so the OS can complete what its currently doing on the drive.
Its probably viable to use a sled that has a clear indication
of drive activity, so you dont actually pull it out when the
OS is using the drive. Thats tricky tho because just because
XP isnt currently using the drive doesnt mean that it wont
try in the instant you have unplugged it. No big deal if its
just doing a read as it does for various reasons, but not
a good idea with a write.
Probably best to concentrate on the sleds themselves and
concentrate on the name brands like Kingwin and only use
a sled thats advertised as supporting hot swapping.
There are some systems that document that quite well with
RAID, but not many at all that do that that with non RAID.
What you are seeing is the classic downsides of operating on the
bleeding edge of computing technology. Quite a bit of bleeding.
Anyway, I want to hear from guys that are involved with the same
thing. If you are hot-swapping SATA drives, please reply and let us
(me and the Usenet community) know your story. What can you
tell us about your experience? What do we need to know?
Oh, and for the record, I am talking about Windows XP Pro.
.
- References:
- Seeking information on SATA hard drive hot-swapping . . .
- From: Stan Shankman
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