Port multiplier

Port multiplier

[Richard Scobie]

Hi Tejun,

I am about to start experimenting with SATA PMP and have spent some time
on the net collecting information, including your WIKI.

Please can you help me with a few of missing bits.

I have ordered an ASUS M2N SLI Deluxe which in addition to the NVIDIA
SATA controller, has a JMicron 363 SATA controller which handles one
internal SATA connector and an external eSATA connector.

My understanding is that the JMicron will work using kernel AHCI support
and the board BIOS has an AHCI setting.

My hope is to be able to connect an Addonics AD5APM-E 5 disk port
multiplier module to this. From the photo and some other information at
their website, this appears to use either a Silicon Image 3124 or 3132 chip.

Do you think this will work, if I use the current patch 20060710 on your
Wiki?

If so, and it supports hotplugging, which I believe it may do, what
exactly does this mean?

Can I power up an external enclosure containing the Addonics and 3
drives, configured as a RAID 5 and plug it straight into the running system?

If so, can this be set up to mount automatically?

Can I unmount the connected and mounted array and just unplug the array
with no further concern?

I hope I have not wasted your time by asking this. If the information is
elsewhere, please let me know.

Kind regards,

Richard Scobie

Re: Port multiplier

[Tejun Heo]

Hello,

Richard Scobie wrote:
> I have ordered an ASUS M2N SLI Deluxe which in addition to the NVIDIA
> SATA controller, has a JMicron 363 SATA controller which handles one
> internal SATA connector and an external eSATA connector.
> 
> My understanding is that the JMicron will work using kernel AHCI support
> and the board BIOS has an AHCI setting.
> 
> My hope is to be able to connect an Addonics AD5APM-E 5 disk port
> multiplier module to this. From the photo and some other information at
> their website, this appears to use either a Silicon Image 3124 or 3132 
> chip.
> 
> Do you think this will work, if I use the current patch 20060710 on your
> Wiki?

PMP support for AHCI isn't yet included in PMP patches, so, no, it won't.

> If so, and it supports hotplugging, which I believe it may do, what
> exactly does this mean?
> 
> Can I power up an external enclosure containing the Addonics and 3
> drives, configured as a RAID 5 and plug it straight into the running 
> system?

Yeap.  libata should detect the new drives and attach them.

> If so, can this be set up to mount automatically?

Well, the kernel detects the device and notifies hotplug.  The rest is 
upto how hotplug is configured.

> Can I unmount the connected and mounted array and just unplug the array
> with no further concern?

The machine will survive and detach the device correctly but 
yet-unwritten data will be lost.

-- 
tejun

Re: Port multiplier

[Jim Paris]

Tejun Heo wrote:
> Richard Scobie wrote:
>
> >Can I unmount the connected and mounted array and just unplug the array
> >with no further concern?
> 
> The machine will survive and detach the device correctly but 
> yet-unwritten data will be lost.

He said he'll unmount it first, so presumably that should avoid most
data loss?  I suppose if you're in the middle of a RAID resync, or
just ran fdisk or fsck or similar, you could still have unflushed
data.  Does that mean that hot-unplug is not recommended, and one
should always do warm-unplug instead?

-jim

Re: Port multiplier

[Tejun Heo]

Jim Paris wrote:
> Tejun Heo wrote:
>> Richard Scobie wrote:
>>
>>> Can I unmount the connected and mounted array and just unplug the array
>>> with no further concern?
>> The machine will survive and detach the device correctly but 
>> yet-unwritten data will be lost.
> 
> He said he'll unmount it first, so presumably that should avoid most
> data loss?

Ah... missed that line.

> I suppose if you're in the middle of a RAID resync, or
> just ran fdisk or fsck or similar, you could still have unflushed
> data.  Does that mean that hot-unplug is not recommended, and one
> should always do warm-unplug instead?

If you have unmounted and none of fdisk/fsck/RAID resync or anything 
similar is running (which is true most of the time), hot unplugging is 
just fine.

-- 
tejun

Re: Port multiplier

[Richard Scobie]

Tejun Heo wrote:

> PMP support for AHCI isn't yet included in PMP patches, so, no, it won't.

I shall look forward to development in this area.

Thanks for your efforts do date.

Regards,

Richard