Freeing Disk from VMware Virtual Flash Read Cache (vFRC)

I was toying with vFRC in my lab and when I was done, I deleted the volume from the vSphere web client, but the local flash disk had retained its GPT partition format and was still claimed as a VMFS volume. I was unable to use that disk for other applications.

Try deleting using the web client:

 
Select the host then go to Manage tab then select Storage option and from there choose the Storage Devices entry. Select the disk, then click on the gear icon and choose Erase Partitions. Make sure you selected the right disk because this will wipe everything.


Via CLI: To delete the disk partition, first enable SSH on the host, then login and list all disks:
 ls -l /vmfs/devices/disks/

Sample output:
ls -l /vmfs/devices/disks/
total 495867432
-rw-------    1 root     root     8004304896 Feb 29 08:45 mpx.vmhba32:C0:T0:L0
-rw-------    1 root     root       4161536 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:1
-rw-------    1 root     root     262127616 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:5
-rw-------    1 root     root     262127616 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:6
-rw-------    1 root     root     115326976 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:7
-rw-------    1 root     root     299876352 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:8
-rw-------    1 root     root     2684354560 Feb 29 08:45 mpx.vmhba32:C0:T0:L0:9
-rw-------    1 root     root     128035676160 Feb 29 08:45 t10.ATA_____ADATA_SP600_____________________________7F1820011415________
-rw-------    1 root     root     128033579008 Feb 29 08:45 t10.ATA_____ADATA_SP600_____________________________7F1820011415________:1
-rw-------    1 root     root     120034123776 Feb 29 08:45 t10.ATA_____KINGSTON_SV300S37A120G__________________50026B7255068D61____
-rw-------    1 root     root     120032591872 Feb 29 08:45 t10.ATA_____KINGSTON_SV300S37A120G__________________50026B7255068D61____:1
lrwxrwxrwx    1 root     root            20 Feb 29 08:45 vml.0000000000766d68626133323a303a30 -> mpx.vmhba32:C0:T0:L0
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:1 -> mpx.vmhba32:C0:T0:L0:1
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:5 -> mpx.vmhba32:C0:T0:L0:5
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:6 -> mpx.vmhba32:C0:T0:L0:6
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:7 -> mpx.vmhba32:C0:T0:L0:7
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:8 -> mpx.vmhba32:C0:T0:L0:8
lrwxrwxrwx    1 root     root            22 Feb 29 08:45 vml.0000000000766d68626133323a303a30:9 -> mpx.vmhba32:C0:T0:L0:9
lrwxrwxrwx    1 root     root            72 Feb 29 08:45 vml.010000000035303032364237323535303638443631202020204b494e475354 -> t10.ATA_____KINGSTON_SV300S37A120G______________                                   ____50026B7255068D61____
lrwxrwxrwx    1 root     root            74 Feb 29 08:45 vml.010000000035303032364237323535303638443631202020204b494e475354:1 -> t10.ATA_____KINGSTON_SV300S37A120G____________                                   ______50026B7255068D61____:1
lrwxrwxrwx    1 root     root            72 Feb 29 08:45 vml.01000000003746313832303031313431352020202020202020414441544120 -> t10.ATA_____ADATA_SP600_________________________                                   ____7F1820011415________
lrwxrwxrwx    1 root     root            74 Feb 29 08:45 vml.01000000003746313832303031313431352020202020202020414441544120:1 -> t10.ATA_____ADATA_SP600_______________________                                   ______7F1820011415________:1


Find your disk there, and then list its partitions:
partedUtil getptbl /vmfs/devices/disks/

Sample output:
 partedUtil getptbl /vmfs/devices/disks/vml.010000000035303032364237323535303638443631202020204b494e475354
gpt
14593 255 63 234441648
1 2048 234440703 AA31E02A400F11DB9590000C2911D1B8 vmfs 0

You can see above that there's one partition labeled as "vmfs" which we need to get rid of. The leading number (in blue) is the partition number.

To delete the partition:
partedUtil delete /vmfs/devices/disks/

Sample output:
partedUtil delete /vmfs/devices/disks/vml.010000000035303032364237323535303638443631202020204b494e475354 1

Done. Look in vSphere web client and it should now report 0 primary partitions on that disk and you're free to use it for something else.

Check the partition table:
partedUtil getptbl /vmfs/devices/disks/vml.010000000035303032364237323535303638443631202020204b494e475354
gpt
14593 255 63 234441648

NVMe SSDs, Motherboards and i7 Limitations

TL;DR

Do not buy 2x NVMe disks and plug into M.2 ports if you want max speed. (TL;DR = Too long; did not read = very short summary provided).

Quick Into

For the past month or more I've been hunting for a new laptop to replace my 4-year old Asus gaming laptop & I've been reading a lot about new hardware.

Most shiny new toy is SSD & Non-Volatile Memory Express (NVMe), particularly, the Samsung Pro 950 which can do 2500 MB/s reads & 1500 MB/s writes, where normal SSDs can do 550 MB/s max. This is because the 950 is an NVMe which uses PCIe slots, not SATA slots.

Technical Details

I noticed that the majority of the laptops are designating only 1 slot as NVMe & another as SATA only, even when both are M.2 PCIe slots. This means only one can be used for the Samsung 950 & get max speed, while the other will function at SATA speed only. The most advanced Intel chipset available for Input/Output devices today is the HM170 which offers 16 PCIe lanes. (more lanes = more devices can connect to the PCIe bus).

However, Asus is releasing a new laptop "ASUS ROG G752VY-DH78K" which has a new Intel chipset: the CM236. This chipset offers 20 PCIe lanes! 4 more than the HM170, and an M.2 port supporting NVMe requires exactly 4 PCIe lanes, but the big catch is that any Intel Skylake processor (i7-6820HK or i7-6700HQ) only has 16 PCIe lanes!

So even though you can plug a 950 NVMe on both M.2 slots, they will be sharing the bus towards the CPU, and you will not get max speed of both at the same time, if there are other devices also using the 16 PCIe lanes, such as graphics cards (and you're likely to have one anyway).

This is valid for desktops as well since the above limitation comes from the i7 Skylake architecture.

Conclusion

If you plan on putting both M.2 slots in RAID0 or do some sort of dual access on them using NVMe disks, you will not see max speed of both.

Desktops

If you have a desktop, your motherboard might have a built-in M.2 slot, which would have dedicated 4x PCIe lanes. You can use a PCIe-to-M.2 adapter to plug an M.2 NVMe into a PCIe card in a standard PCIe bus. This way you should get max speed of both NVMe disks since the bus is not shared and all lanes are dedicated.

If you're using graphics cards in SLI mode, then maybe it would start sharing the bus with them. Watch out from that.

Links & References

• http://store.asus.com/us/item/201510AM090006013/A30933
• http://www.xoticpc.com/asus-g752vydh78k-eta-dec-2015-p-8744.html?startcustomization=0
• http://ark.intel.com/products/90584/Intel-GL82HM170-PCH
• http://ark.intel.com/products/90593/Intel-GL82CM236-PCH
• http://ark.intel.com/products/88969/Intel-Core-i7-6820HK-Processor-8M-Cache-up-to-3_60-GHz
• http://ark.intel.com/products/88967/Intel-Core-i7-6700HQ-Processor-6M-Cache-up-to-3_50-GHz
• https://en.wikipedia.org/wiki/Platform_Controller_Hub

Firefox Crashing When Searching And Playing Flash

I've been having this problem for quite sometime now with various versions of Firefox (3.5.7 here as of this writing).

Problem description: When there's something playing, or has already played with flash content (like youtube videos), and then I attempt to search for text in a page and that text is NOT found, the browser crashes (segfault).

I found 2 solutions to this, one of them seems more of a workaround rather than a solution, and the real problem seems to be coming from Adobe's Flash plugin for Linux (they just can never get it right...).

Solutions:

1. Turn off search sound: open a tab and in the address type: about:config
   look for sound and then disable: accessibility.typeaheadfind.enablesound by double clicking it, then restart your browser.
2. Use nspluginwrapper along with Adobe's libflash package. Whether the search sound is enabled or disabled, this should work just fine.

Javascript Menu Fall Behind Flash: Fixed!

I used to face a problem before when browsing websites with flash animations under a menu, when the mouse goes over a menu item, the sub-menu drops behind the flash animation, and I can't click anything.

I thought it was caused by poor design of the website, where they could've used the Z-Index property in Cascading Style Sheets.

According to this page, z-index wouldn't even solve it, and the problem was actually caused by Flash Player 9 on Linux (only).

I grabbed a copy of Flash Player 10 and installed it, and now everything works as it should!

I run Kubuntu 8.04 and installed the package manually. Download the ".deb" package then run this command:

sudo dpkg --install install_flash_player_10_linux.deb

After the installation is over, restart firefox and the new flash player will be loaded.