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* Serial ATA (SATA) status report
@ 2004-02-26  2:34 Jeff Garzik
  2004-02-26  2:54 ` Mike Fedyk
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Jeff Garzik @ 2004-02-26  2:34 UTC (permalink / raw)
  To: Linux Kernel

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Serial ATA (SATA) for Linux
status report
Feb 25, 2004


Hardware support
================


Intel ICH5 and ICH5-R
---------------------
Summary:  No TCQ.  Looks like a PATA controller, but with a few added,
non-standard SATA port controls.  Hardware does not support hotplug.
"Coldplug" support is potentially feasible.

libata driver status:  Production, but see issue #2, #3, #4.

drivers/ide driver status:  Production, but see issue #1, #2.


Issue #1:  Depending on BIOS settings, IDE driver may lock up computer
when probing drives.

Issue #2:  Excessive interrupts are seen in some configurations.

Issue #3:  "Enhanced mode" or "SATA-only mode" may need to be set in BIOS.

Issue #4:  Driver disables SATA port on unload, but does not re-enable
SATA port on load.


Intel ICH6 ("AHCI")
-------------------
Summary:  Per-device queues, full SATA control including hotplug
and PM.

libata driver status:  "looks like ICH5" support available in ata_piix
very soon.  Full support available in a week or two.


Promise TX2/TX4/SX4
-------------------
Summary:  Per-host queues on all controllers.  Full SATA control
including hotplug and PM on all but one controller.

libata driver status:  Beta, but see issue #5.


Issue #5:  Some boards appear to have PATA as well as SATA ports.  PATA
is not currently supported, and no plans have yet been made to rectify
this.  Ideally drivers/ide would drive PATA, but if they are the same
PCI device, that would not be feasible.


Silicon Image 3112/3114
-----------------------
Summary:  No TCQ.  Looks like a PATA controller, but with full SATA
control including hotplug and PM.

libata driver status:  Alpha.

drivers/ide driver status:  Production, but see issue #4.

Issue #4:  Need to have the most recent fixes posted to lkml, for stable
operation and full performance (where possible).


Silicon Image 3124
------------------
Soon, hopefully.  User-written.


Broadcom/ServerWorks/Apple
--------------------------
Summary:  Huge per-device queues, full SATA control including hotplug
and PM.

libata driver status:  Beta.


VIA
---
Summary:  No TCQ.  Looks like a PATA controller, but with full SATA
control including hotplug and PM.

libata driver status:  Beta.


SiS
---

libata driver status:  in progress (user-written)


Vitesse
-------

libata driver status:  in progress


Marvell
-------
libata driver status:  in progress




Software support
================


Basic Serial ATA support
------------------------
The "ATA host state machine", the core of the entire driver, is
considered production-stable.

The error handling is _very_ simple, but at this stage that is an
advantage.  Error handling code anywhere is inevitably both complex and
sorely under-tested.  libata error handling is intentionally simple.
Positives:  Easy to review and verify correctness.  Never data
corruption.  Negatives:  if an error occurs, libata will simply send
the error back the block layer.  There are limited retries by the block
layer, depending on the type of error, but there is never a bus reset.

Or in other words:  "it's better to stop talking to the disk than
compound existing problems with further problems."

As Serial ATA matures, and host- and device-side errata become apparent,
the error handling will be slowly refined.  I am planning to work with a
few (kind!) disk vendors, to obtain special drives/firmwares that allow
me to inject faults, and otherwise exercise error handling code.



Queueing support
----------------
Even though some SATA host controllers on the market already support
command queueing (a.k.a. "TCQ"), libata does not yet support it.

However, libata was designed from the ground-up to support queueing, so
I need only change a few lines of code, and write two functions, to
enable this behavior.

Queueing will be enabled in libata soon, but to do so requires a long
stretch of testing on a large variety of controllers and drives.  This
is very time-intensive, and is the largest part of this task.


Tangent:  Host-based queueing and Native Command Queueing

Queueing is the process of sending multiple commands to a single device,
without waiting for prior commands to finish.  This increases
performance and reduces latency.  There are three types of queueing in
the ATA world:

1) "legacy TCQ" -- some PATA devices support this.  Just ignore it,
it's going away.

2) "host-based TCQ" -- the host controller supports a queue of drive
commands, whether or not the drive supports it.

3) "Native Command Queueing" -- both host and drive cooperate in the
queueing and execution of drive commands.  This should provide the
highest performance and lowest latency of all three options.


#1 is support by drivers/ide _only_.  libata will not support this.
#2 will soon be supported by libata.
#3 will be supported by libata when hardware is available from drive
manufacturers.


Hotplug support
---------------
All SATA is hotplug.

libata does not support hotplug... yet.



Power Management support
------------------------
Over and above the power management specified in the ATA/ATAPI
specification, one can aggressively control the power consumption of
SATA hosts, the SATA bus, and the SATA device.



SMART support
-------------
Soon.  Requires the capability to directly submit ATA commands from
userspace to the low-level device, which must be added with care.



^ permalink raw reply	[flat|nested] 15+ messages in thread
* Re: Serial ATA (SATA) status report
@ 2004-02-26  6:28 Kyle Wong
  0 siblings, 0 replies; 15+ messages in thread
From: Kyle Wong @ 2004-02-26  6:28 UTC (permalink / raw)
  To: linux-kernel

Dear Jeff,

Is there following 3112/3114 problem exist with latest kernel 2.6.x? or
"Issue #4:  Need to have the most recent fixes posted to lkml, for stable
operation and full performance (where possible)." suppose to fix this?

http://docs.freebsd.org/cgi/getmsg.cgi?fetch=1621281+0+/usr/local/www/db/tex
t/2003/freebsd-current/20031130.freebsd-current

http://docs.freebsd.org/cgi/getmsg.cgi?fetch=4276497+0+/usr/local/www/db/tex
t/2004/freebsd-current/20040208.freebsd-current

Also, for ICH5, "Issue #2:  Excessive interrupts are seen in some
configurations."

Is there any fix? W'll I get problems if I use 2 x PATA + 2 x SATA drives
with ICH5 in enhanced mode?

Thanks.




^ permalink raw reply	[flat|nested] 15+ messages in thread
* RE: Serial ATA (SATA) status report
@ 2004-02-26 19:08 Adam Radford
  0 siblings, 0 replies; 15+ messages in thread
From: Adam Radford @ 2004-02-26 19:08 UTC (permalink / raw)
  To: 'Mark Watts', Terje Kvernes; +Cc: Andre Tomt, Linux Kernel

The only 'issue' running in 64-bit mode on AMD-64 I know of was where there
was data corruption when the IOMMU flushing scheme changed.  I think Andi
sent out an email
where this was reverted.  If it wasn't, all you need to do is run with
iommu=fullflush
and you shouldn't have any other trouble.

What other issues are there?

-Adam

-----Original Message-----
From: Mark Watts [mailto:m.watts@eris.qinetiq.com]
Sent: Thursday, February 26, 2004 7:56 AM
To: Terje Kvernes
Cc: Andre Tomt; Linux Kernel
Subject: Re: Serial ATA (SATA) status report


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>   the 3w-xxxx-module works well enough in 32bit mode on AMD64.  sadly
>   enough, we have had some other issues with 64bit mode, but the
>   _driver_ seems to load there as well.

Do these 'issues' prevent the cards from being used at all in 64bit mode on 
AMD-64?

We'd really like to use the 4-port SATA 3Ware card on a Tyan Thunder K8W 
(S2885) but it'd be a bit of a waste if we can only use it in 32bit mode. (I

assume 32bit mode means you compile for i686 instead of AMD-64 ?)

Mark.

- -- 
Mark Watts
Senior Systems Engineer
QinetiQ TIM
St Andrews Road, Malvern
GPG Public Key ID: 455420ED

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^ permalink raw reply	[flat|nested] 15+ messages in thread
end of thread, other threads:[~2004-03-01  8:05 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-02-26  2:34 Serial ATA (SATA) status report Jeff Garzik
2004-02-26  2:54 ` Mike Fedyk
2004-02-26  3:09   ` Jeff Garzik
2004-02-26  9:13 ` Mark Watts
2004-02-26 13:19   ` Andre Tomt
2004-02-26 14:23     ` Mark Watts
2004-02-26 15:33       ` Terje Kvernes
2004-02-26 15:55         ` Mark Watts
2004-02-26 20:11           ` Terje Kvernes
2004-02-27 18:56       ` Mark
2004-02-26 16:00   ` Jeff Garzik
2004-02-28 14:49 ` Justin Cormack
2004-03-01  8:05   ` Michael Knigge
  -- strict thread matches above, loose matches on Subject: below --
2004-02-26  6:28 Kyle Wong
2004-02-26 19:08 Adam Radford

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