Dual and Single Channel Mode

Talking about dual channel and single channel. Is it a theory or is it really a big significant difference in performance between the two? Just curious

Hi Richard,
Thanks for the speedy reply. I'll go tinker around a little more and see what I can do with this board
Benedict.

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Difference between emergency state and single user mode ?

Hi,
I want to know the difference between emergency state which we normally use in suspect mode database and single user mode.
Navakanth

Emergency/suspect mode is tells you the state of the database and database is not available for user action but where as single user mode tells the user action preference. Database is active and available for the user action.
You can refer
http://msdn.microsoft.com/en-us/library/bb522682.aspx
EMERGENCY
The database is marked READ_ONLY, logging is disabled, and access is limited to members of the sysadmin fixed server role. EMERGENCY is primarily used for troubleshooting purposes. For example, a database marked as suspect due to a corrupted log file can be
set to the EMERGENCY state. This could enable the system administrator read-only access to the database. Only members of the sysadmin fixed server role can set a database to the EMERGENCY state.
SINGLE_USER
Specifies that only one user at a time can access the database. If SINGLE_USER is specified and there are other users connected to the database the ALTER DATABASE statement will be blocked until all users disconnect from the specified database. To override
this behavior, see the WITH <termination> clause.
The database remains in SINGLE_USER mode even if the user that set the option logs off. At that point, a different user, but only one, can connect to the database.
Before you set the database to SINGLE_USER, verify the AUTO_UPDATE_STATISTICS_ASYNC option is set to OFF. When set to ON, the background thread used to update statistics takes a connection against the database, and you will be unable to access the database
in single-user mode. To view the status of this option, query the is_auto_update_stats_async_on column in the sys.databases catalog view.
If the option is set to ON, perform the following tasks:
Set AUTO_UPDATE_STATISTICS_ASYNC to OFF.
Check for active asynchronous statistics jobs by querying the sys.dm_exec_background_job_queue dynamic management view.
If there are active jobs, either allow the jobs to complete or manually terminate them by using KILL STATS JOB.
--Prashanth

Won't boot normally or in recovery and single user mode, safe mode hangs up halfway

iMac locked up with visual glitches while playing the Mac beta client of League of Legends. Had to force a shutdown by holding the power button. Now it won't boot; after the Apple logo and spinning wheel I just get a white screen. I tried launching in recovery mode, that didn't work. Then I tried safe mode; the bar filled a little over half and then nothing but white screen. I was able to boot single user mode once; ran fsck -fy and rebooted, still white screen. Now I can't get back to single user mode. I booted with command option P R to reset the NVRAM and got the second chime, but still nothing.
Luckily all my important files are in the cloud, but I'm really hoping my computer isn't completely dead. I haven't had any issues in the past. I've even been playing LoL for over a month with no issues, until now when I tried to play the newer game types, Dominion and ARAM; both caused visual glitches forcing shutdowns. I was able to restart my computer with no problem after the first two visual glitches, but after the last one I am stuck at the white screen as I described above.
Thanks in advance for your help!

I'd bet the drive is damaged. You could try reformatting if possible. Again, you are booting from the Recovery-10.8.2 disk if you can. If you can't, then you will need to use the installer disc that came with the computer.
Install or Reinstall Lion/Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
      left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
        the Security button and set the Zero Data option to one-pass. Click on
      the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.

Screaming Fans ,10.4.3., and Single User Mode.

I wanted to add my experience with the screaming fan problem and 10.4.3.
When I ran Disk Utility and used the verify disk option I received some minor errors and proceeded to boot the OS X install disk and run Disk Utility from there. When I did I received no errors. Rebooted back to 10.4.3 and reran disk utility and received the same minor errors. So I read one of the Mac sites that stated that one needed to run in single user mode and execute fsck f. This where the fun started.
When I went into single user mode the fans went wild. But I knew this to be normal and proceeded with repairing the disk (which was successful as evident with no errors being reported while booted to the desktop and running live verify disk. But before I got to that point the fans remained screaming after the reboot to 10.4.3. I reset the PRAM and NVRAM but to no avail. The fans would not quite down. The fix turned out to be very simple I unplugged the computer (after shutting down) for about 15 seconds. Re plugged it in and it was fine after that. Fans back to normal! I replicated the problem applied the same fix and again every thing was normal.
I just thought I would pass this on to the iMac community.

Hi Steven, bit unclear on a couple things.
When I went into single user mode the fans went wild. But I knew this to be normal and proceeded with repairing the disk
Normal for fans to go wild in single user or when repairing the disk?
I replicated the problem applied the same fix and again every thing was normal.
The problem being screaming fan and the fix being resetting SMU? (unplug for 15secs). So how did you replicate it, and is it really fixed now?

10.4.3 and Single User Mode, now Wireless Keyboard can

Hello all.
IN case you haven't found out which I did, just to let you know, with the latest OS 10.4.3 update, now you can boot into Single User Mode (fsck) with your
b wireless keyboard
and still at the same time
b continue to complete fsck process with your wireless keyboard!!
No more switching to a regular wired keyboard just to complete the process!
Cheers

Hi Steven, bit unclear on a couple things.
When I went into single user mode the fans went wild. But I knew this to be normal and proceeded with repairing the disk
Normal for fans to go wild in single user or when repairing the disk?
I replicated the problem applied the same fix and again every thing was normal.
The problem being screaming fan and the fix being resetting SMU? (unplug for 15secs). So how did you replicate it, and is it really fixed now?

Password protected EFI and Single User Mode

Hello Community,
if I protect the EFI with a password than the single user mode is disabled. But I thought that I can enter the single user mode by entering the EFI password but no password prompt appears. Only the possibility to change the startup volume is accessible by a password prompt. Do I miss a possibility or is the only way to enter the single user mode by bypassing or disable the password by using the firmware password utility on the installation disk without violence?
BTW: I know the act of violence by changing the RAM configuration but this isn't the way I want to describe in the system documentation
Thx in advance & Bye Tom
Message was edited by: prontosystems

Try holding the Option key while booting. It should ask for the password, then allow any boot options after you select the drive. If you boot from the install DVD (using the Option key and password), you can use the "Utilities" menu to disable the password, after choosing your language.

One Image for dual and single processor G5 machines

I'm working in a lab that has both single and dual processors G5 machines. There is only one image for both machines and I suspect that we have a few bugs with the single processor machines because of this. Has anyone else used one image for both single and dual processors? Have there been problems. I'm wondering if it is necessary to create two separate images.
mdinger

There is not difference in the images, but you might have problems with the single G5 machines and 10.4. Did you do the firmware upgrade?
I have ~10 single G5 and 25 dual D5 machines netinstalled from one image without trouble.
jotjot

Single access point with multiple ssids and single channel possible?

Hi everybody.
I have this silly question.
Let say we have three vlans, vlan1,2,3 and they are mapped to wlans as follows:
Vlan 1 ssid1
Vlan 2 ssid2
Vlan3 ssid 3
AP --------trunk------Switchted network.
Our Ap has mobile devices in three wlans, i.e ssid1ssid2 and ssid3
Since AP uses half duplex mode, mobile devices need positive ack from ap before they can send data, therefore once channel let say channel 3( assuming 802.11b is used) can be shared by all mobile devices in three wlans.
Is my understanding correct?
Thanks and have a great weekend.

Hii ,
Yes ,that is pretty much possible as suggested by other experts on board. Depending on your access point you will have 1 (2.4 GHz) or both 2.4 & 5GHz radios.
You can configure multiple SSIDs (up to 16 ) known as MBSSID mode in autonomous environment. In Controller based architecture you can configure up to 512 WLAN (SSID) and transmit any 16 of them per AP (using AP group feature). However , it is recommended to keep multiple SSID count below 8 as for each SSID separate beacon will be sent on air which consumes more air time.
Hope this helps
Thanks
Vinay

Setxkbmap and single layout mode

Hi everyone!
I have noticed that I can't use some hotkeys, like Ctrl-c or Ctrl-v (and many others) when I'm switching to the single 'ru' layout:
$ setxkbmap ru -model pc104
It happens since a produced keysym belongs to the cyrilic set:
$ xev -event keyboard | grep state
state 0x10, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
state 0x14, keycode 54 (keysym 0x6d3, Cyrillic_es), same_screen YES,
One of possible workaround that I have found is to set specific variant. Well... it simply fails:
$ setxkbmap ru -model pc104 -variant alt-int
Error loading new keyboard description
But when I'm adding another layout all seems work:
$ setxkbmap ru,us -model pc104 -variant alt-int
Keysyms are all valid in that case:
$ xev -event keyboard | grep state
state 0x10, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
state 0x14, keycode 54 (keysym 0x63, c), same_screen YES,
So I'm here to find out if it is a bug, or feature? Can someone please explain to me it? Since I can't find any references to this behavior.
Thanks,
Max

Does it work without -model pc104 (and why do you add that option)?

Ni 6111 and Single Scan mode - any example code

Hi,
I am using the Measurement Hardware Driver Development Kit (MHDDK) to program an NI 6111. I just cannot work out how to get
single scan to work. No matter what I do, I either get no conversions or a full FIFO.
The example code does not include any Single Scan examples and I would be extremely grateful if someone could provide me with example code.
thanks
Russell Thamm

Hi Russell-
Is there a reason why you have decided to perform register-level programming with this device? It is supported by NI-DAQmx for Windows and NI-DAQmx Base for Linux and Mac.
Regardless, if you would like to request support for the MHDDK I would encourage you to repost your question on the DDK Forum.
Hopefully this helps-
Tom W
National Instruments

Problem running ddr3 dual channel mode on MSI X48C Platinum

I am having a problem with running my ram in dual channel mode, in single channel mode it works with out a problem, i switch the ram slots for dual and it does not boot
Can any one give me an answer to why it wont work?
Also having problems with my Q9300 not working with the ram
Processer: Intel core 2 duo E7300 (ES) @ 2.66Ghz OC @ 3.0Ghz
Ram:Corsair: 2x4GB CMZ8GX3M2A1600C9
Motherboard:Msi x48c Platinum
Vid Card:XFX Radion HD6850 XXX edition 1GB GDDR5
PSU:Ultar 600W
HDD:Western Digital 500GB 7200RPM

Also see this thread, https://forum-en.msi.com/index.php?topic=152802.0
Quote
The motherboard overview states: http://www.msi.com/product/mb/X48C-Platinum.html#/?div=Detail
Quote
• Supports four unbuffered DIMM of 1.5 Volt DDR3 800/1066/1333/1600 DRAM, 8GB Max
• Supports two unbuffered DIMM of 1.8 Volt DDR2 667/800 DRAM, 4GB Max
With the last BIOS, it states that 4GB modules may be possible, but looking at the memory test report http://www.msi.com/file/test_report/TR10_1393.pdf it seems this was only done for DDR2 modules, as these are the only ones reflecting this.
Suggest you check with MSI technical if the BIOS should accommodate DDR3 4GB modules as well. >>How to contact MSI.<<
Do a CMOS clear, then once in the BIOS, set your DRAM ratio so that the DRAM is at 1066. See if that works.

Can't get Dual Channel mode to work

Hello,
I have a pair of 512MB DDR400 ram sticks (listed in my sig).
The Memory Slots are arranged like this:
1 2 3
[cpu] | | |
I put each stick in slot 1 and 2 and no workie, still Single Channel Mode.
I put a stick in slot#2 and #3, no workie.
I put a stick in slot#1 and slot#3, no workie.
Is there something else that I'm missing or did I just buy the wrong memory for dual channel operation? It was not a matched set, but it is the same no-name brand of memory I bought from newegg.com. They both have the same 3225804T-5 marking on them...
They are supposed to be 2.5CS and that is what my bios is set to. I don't have any special settings in the bios that I know of..
Let me know if you have any ideas or if I need to post more information.
Thank You!

K7N2-V
Not sure about this but is that motherboard based on the Nvidia nForce2 400 chipset?
What does the manual specs say?
If it is then it doesnt have 2 memory controllers and can only do single channel.
Edit: http://www.pcper.com/specs.php?p=MB&id=38
That your mobo?

Can I operate my new laptop in dual channel mode? 15-n216us

Hi,
I have a new HP touchscreen 15.6" model 15-n216us. It came equipped with a 4GB memory stick and one open slot. I purchased an "identical" stick and installed it with no problems. ("Identical" means same manufacturer - Kingston -, same size, numbers, etc... but they are not "twins" per se.)
I ran CPU-Z before and after the install and both times it showed the laptop running in single channel mode. I swapped the sticks into opposite slots and ran it again. Each time it shows 8GB memory running single channel.
So, my question is this. Is this machine capable of running in dual channel mode? (And it not, where would I have found this myself?) If it does, does this mean that I have to buy "twins" ... ie two new paired 4GB sticks? And lastly, am I really missing much by not running dual channel mode?
Thanks!
-CD

From the Service Manual:
DDR3L-1600-MHz dual channel support
Can we have the two Kingston stock numbers for the memory modules? Generally to run dual channel they do have to be identical and a difference in latency or any other parameter can block dual channel operation.

Single User Mode Question

I use single user mode to do fsck because doing it on a live disk takes way too long. I was wondering if there is a way to repair permissions from single user mode. Thanks

1. what does AFAIK mean?
As Far As I Know
2. What I have gathered is that it is near next to y difficult to repair permission fro the CLI and single user mode.
Correct. You can't use diskutil because the disk framework isn't loaded. You can do it if you're booted from an install DVD, though.

Why won't single user mode recognize /sbin/mount command?

I need help from people who are knowledgable abou these Mac wonders of the world and single user mode.
I'm trying for the life of me to run "memtest" in single user mode and am finding it impossible.
After I boot into single user mode, I get a "Shell>" prompt.
I type in /sbin/fsck/ -y to do some check thing. I then type in /sbin/mount -uw /
Both times I get an error saying that "/sbin/yada yada yada is not recognized as an internal or external command, batch or whatever"
No command work at all. I have no clue what I'm doing and am using instructions from where I got the memtest app. Sure I could just run it from the Terminal but then you're not testing all of the RAM, only the available portion. There's a huge chunck that won't be tested as OSX is using it. I want to do this as I just upgraded RAM to 8G with Crucial and now my MBP is acting very slow and weird.
HELP???? Why does this have to be sooooo hard.

I found the solution to the problem. Somone on a different forum had the same issue at one time. The problem is my use of Refit. When you hold Command-S at start when using refit you go into a single user type mode inside the refit shell. So it is something different.
Instead I needed to let the Mac boot Refit like normal. With the Mac partition highlighted press "F2" and it will display boot options for the Mac partition. One of them is Mac OSX single user mode. Simply select and hit enter and then I enter the correct single user mode and I'm off.
Then everything works like it should. I was my own undoing with my use of Refit.

Dual and Single Channel Mode

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