Tag Archives: hard disk

How to find out the LUN id of a Windows disk

Posted by on April 27, 2018 No comments
Hard Drive

Attaching multiple LUNs to a Windows host and later trying to figure out which LUN is which can be a drag. I found out that using the “details disk” command in diskpart can help you finding backup the right LUN:

 

diskpart

list disk

select disk 19 (or whatever drive you want to see the details of)

detail disk

HITACHI DF600F  Multi-Path Disk Device
Disk ID: 00000000
Type   : FIBRE
Status : Online
Path   : 0
Target : 2
LUN ID : 7
Location Path : UNAVAILABLE
Current Read-only State : Yes
Read-only  : Yes
Boot Disk  : No
Pagefile Disk  : No
Hibernation File Disk  : No
Crashdump Disk  : No
Clustered Disk  : No

There are no volumes.

 

So in this particular case the Host LUN id was 7. This should help you along a bit 🙂

Format of CSV on Hyper-V hosts is very slow

Posted by on April 6, 2018 No comments
Hard Drive

When formatting a newly added disk (LUN) to Hyper-V, often you’ll notice the formatting takes forever. Dell EMC therefore advises to disable VAAI on VMware hosts for the same issue, however modern VMware hosts don’t seem to have this problem. Hyper-V however still have this issue. To disable the UNMAP / TRIM from happening, use the following command:

fsutil behavior set DisableDeleteNotify 1

After formatting was performed, you’ll need to re-enable UNMAP / TRIM by issuing the following command:

fsutil behavior set DisableDeleteNotify 0

 

EMC Unity: simplicity redefined

Posted by on May 2, 2016 1 comment
EMC Unity

It’s been a while since the VNX2 was born: September 2013, I remember it very well. Being a part of the EMC Elect, I was invited to be at the actual launch in Milan (Italy) and what a ride it was! The whole launch was wrapped around Formula 1 technology and it sure was “speed 2 lead“. That “old” VNX2, which I’m still perfectly happy with by the way, was a revolution in my humble opinion: multi-core everything, in short MCx. And yes, it was like everything just went faster, smoother and better.

New technologies

But with new technologies popping up every so many months now, it was time for a new mid-range storage array. Flash storage isn’t a novelty anymore, it’s a must! And the “old” hybrid arrays were fine, but needed some fine-tuning. With flash devices growing bigger every quarter or half a year and faster as well, the whole back-end needed an upgrade. The old 6 Gb back-end (x4) needed an upgrade.

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The next big merger? Western Digital wants to buy SanDisk!

Posted by on October 21, 2015 No comments
WD SanDisk

According to rumors Western Digital would love to buy SanDisk for $19B. Multiple companies are interested in buying SanDisk, but it’s WD that seems to have the advantage. The deal will perhaps already take place during next week!

Micron also interested

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SCSI, (P)ATA, SAS, NL-SAS and SATA, what’s the difference? (part 2)

Posted by on April 2, 2013 3 comments

So what else is there that differentiates SCSI, (P)ATA, SAS, NL-SAS and SATA?

Size matters

In part 1 we talked about Rotations Per Minute and Command Queuing, but what else is there that makes a certain drive a better choice than any other? Other differences are the size of the platters. Commonly used are 3.5 inch and 2.5 inch. Although it makes sense that smaller platters can rotate faster than larger platters in the end only the size of the drive cage matters. It’s in fact somewhat weird that most 2.5 inch drives now rotate at 10k RPM and the 3.5 inch drives at 15k. Being able to cool the device is probably the main reason why a 10k drive only spins at 10k RPM. If it would rotate any faster, it would heat up more and heat dissipation could become a serious problem. So if you need a high GB per square meter density and performance doesn’t really matter, then the 2.5 inch drives make sense, but if performance is the key differentiator, the more IOps you can squeeze out of each drive, the better. And since we’re not discussing data center designs here, only quality / performance counts.

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