If it is the same, your question has been answer as YES.
#Softraid split mirror software
Do your software mirroring in Windows and check with diskpar -i 2 again to see if it is the same as the lastest result. at the command prompt, type: diskpar -i 2 again and you should see the partition has been aligned from the output result. Now you should see the 64K aligned partition created in Disk Management console. Now type create partition primary align=64 Type select disk 2 on the diskpart prompt. take note of the disk number you want to align the partition, for instance your chosen disk number is 2 at the diskpart prompt type list disk (diskpart>list disk) Here's the command:ĭiskpar -i 2 (2 is the disk number where you can also see it in disk management console). You need diskpart.exe from Windows 2003 SP1 to set the partition align and diskpar.exe from Windows 2000 to check the partition info such as starting offset, partition length and hidden sector, etc. To confirm that I suggest you do it in your lab environment. To answer your original question, the Windows software mirror will create the mirror volume on the aligned partition that you created with diskpart because when you align the partition with diskpart, it will tell the Windows where to start writing the data on the under lying disk geomatry. For SIS however, that's a different story, the level of compression available with the blocks correctly aligned is, imho, an overriding reason to go through this process. The reason, of course, is the VMFS -> VMDK layers of virtualization are totally removed now it's only LUN -> Partition (which is exactly how it worked before VMW came along).Īgain, just stressing the point, I would never go through this pain for performance, the IO gained by correctly aligning the blocks seems to be very insignifciant, not at all worth the effort. In the NTAP space, RDMs are correctly aligned (assuming that you select the right type of OS when you create the LUN). With a raw LUN (RDM) interestingly, we don't have to do these steps. Take a look at tr-3593 (NTAP document) to see a much better diagram of all the layers in the storage stack, as well as an explination of why this happens (again it's something that all storage arrays deal with in a virtualized envrionment).
![softraid split mirror softraid split mirror](https://fedoramagazine.org/wp-content/uploads/2019/05/raid_mirroring.jpg)
The alignment issue is at the very last layer the VMFS is correctly aligned, the VMDK is correctly aligned, it's the Windows partition that is not correctly aligned. Here's the storage layer from the NTAP all the way up to Windows:ĭisk -> Aggregate -> Volume -> LUN -> VMFS -> VMDK -> Partition (Logical Drive). This is similiar to the way that other vendors do it, but because NTAP has the rather unique ability to deduplicate data on disk, the alignment of these blocks becomes much more critical. In the NTAP world, there are many, many layers of storage virtualization, and everything needs to be lined up all the way through the stack to make the blocks actually align on disk. However, that's not where the problem exists, the problem is the alignment of the NTFS partition within the VMDK file (2 more layers of virtulization down). You are right, when you create the VMFS in VC, the alignment of the VMFS is done for you. Thanks for the reply, I am going to test this at some point (the mirroring inside of Windows) to see what I find, however, I am hoping your right! However, with SIS on NTAP, it becomes FAR more important. I would never do this for preformance increases, I have never seen that in my testing to make any appreciable difference in a real work environment. If not, the software is much less effective (because the blocks are all hacked up, basically you need a string of 3 blocks to be identical, rather then just 1 block I can explain it in more detail, if it would be helpful to anyone), more on the order of 10% (100GB turns into 90GB). When we are correctly aligned, the compression ratios can be 70-90% (as in, 100GB turns into 10GB) IF the blocks are correctly aligned. My clients are using NetApp storage, which has a feature called SIS that single instances all indentical blocks on a LUN.
![softraid split mirror softraid split mirror](https://www.pcsteps.com/wp-content/uploads/2015/04/Software-RAID-1-in-Windows-7-for-Increased-Data-Security-27.png)
However, there is another reason to have correctly aligned blocks namley using block level deduplication on the storage array. Performance, imho, is not a reason to go through this process. Actually, your 100% correct, in all the testing I have done I have seen little/no difference in performance between an aligned volume and an incorrectly aligned volume.