Vwware ESX 4 Install For editable datastore block size


I would really like to know how to set up my raid so that I can install ESX 4 in a way that will actually let me adjust the block size of my datastore.

I found out the long way that ESX 4 by default installs a 1MB block size. Then as per Vmware's documentation the resolution is to install 3.5 (which my account won't let me anyway because I am licesensed for 4....never had 3.5 in the first place) and then upgrade to 4.0. This isn't really an option for me.

Then there is something about building a second raid set to install the host and leave the original disc for the vmfs. I wouldn't mind doing this but It also says that there is now way to install the second datastore as the same drive as the GUI...well to save time it is all right here: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1012683

I would just like a way to do this without busting my raid again, it takes hours to rebuild.

Here is my situation. I want to install datastore in 4 MB block sizes. I have a dell r900 with 8 300 GB 10K hard drives and the expandle raid controller. I want to go raid 5. How can I accomplishe ths.

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Do you have VMs/data on the datastore currently? If not, just delete the datastore from vCenter, the re-add the storage with the Block Size you want. If you do have VMs/data on the datastore, migrate VMs/data off the datastore so you can delete/remove it, then re-add with the needed Block Size.

Hope that helps.

badgermikeAuthor Commented:
I should clarify and say I can do what it takes with the raid to create the proper virtual disks. Right now I am pretty much at ground zero and can do anything i need. Should I just install 2 virtual disks, 1 big enough for vmx and 1 for the rest? but I really don't know how it will help to much if I can install on the same dive as the gui - and I can't have a second datastore...uggg..
badgermikeAuthor Commented:
I have nothing right now. I need to re-create my virtual disks and set a raid level. But before I wiped it clean, I tried just remove and re-add the datastore...however it wouldn't let me...the datastore just comes with the host in a defualt 1MB block size...probably somthing to do with:
"The service console in ESX 4.0 runs as a virtual machine on local storage. As such, you cannot reformat this volume.    To resolve this issue, perform one of these workarounds: Re-install the ESX host on a different drive (for example, a second RAID set or boot from SAN), and leave the original disk for the VMFS volume. You can then choose your blocksize when creating the second datastore.  Install ESX 3.5, create the volume with desired blocksize, then upgrade to ESX 4.0. Carve out a new LUN or RAID set on the local controller for a new volume. Add physical disks as necessary.

You cannot create a second datastore on the same drive via the ESX GUI. You must use the following command:

Note: You may need to create a partition on the free space first with fdisk.
vmkfstools -C vmfs -b Xm -S local2mBS /vmfs/devices/disks/naa.xxxxxxxxxx:y   where:"
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This doesn't directly address your question, but is worth mentioning.

You are probably equating this huge block size with improved performance.  You are wrong.  A 4MB block size, by design, requires a 4MB-sized I/O for writes.  Think of all the log and journal files you have.  If anybody so much as reads a file, any file, then all 8 disk drives are going to have to get involved to update 4 whole bytes of data. (the last access time).  Let alone all the journals.

Now for the RAID, you can't change anything w/o doing a backup, rebuilding entire array, and restoring.  The block size, is related to stripe size, and data is laid out based on the settings.

I can not think of too many real-world examples where a 8x300 in 4MB block size will translate to better overall performance, for any operating system.  Only exception would be a data logging application, but even in that environment, you would need to disable file system journaling and boot off of another RAID set with smaller block size, and even then performance would be minimal at best.

Remember, block size and I/Os per second are mutually exclusive.   From a simplistic view, if you quadruple block size by four, then you divide the number of IOPs by 4.  I doubt you want that.

badgermikeAuthor Commented:
thanks for the info, it is not about performance, it is just about dealing with what I currently have....I have a server that is larger than 256 GB thus I need a larger size in order to P2V it.
backup doesn't matter the server is blank and has no configuration or virutal disks anymore...I have no vm's or hosts to deal with....only installing ESX with larger block size
OHHHH....so, you have ESX installed on the same RAID as the datastore?...and I guess the storage is local storage? I assumed you had maybe shared storage. Yeah, you can't delete the datastore, re-add it then. I'm not sure of your disk setup, but here's my recommendation:
Create a RAID1 for the ESX OS install. If you have small size disks (30GB?), that's all you would need. Then, create a RAID5/10..whichever you want, for your datastore/storage. You can then modify the Block Size when you add the storage to your host.
vmwarun - ArunCommented:
The only way of specifying a different block size is by using a scripted installation of ESX using a kickstart file.
If you are using the default installation, you cannot change even the /boot and /vmkcore partitions too. Only changes to /root, /var/log and swap are allowed.
We had this issue in our first test.
Coolsport00 is right.
Create a mirror then create a raid, whatever you want on the second raid. Then you can play with the datastore as you wish.
We did run into issues though. Where if you set the block size small when you initialy build the raid your VM stuff will be moot. So be sure to set your block size when you first build your raid. At least this helped us out.
badgermikeAuthor Commented:
I am going to give it a shot and will get back to you guys...thanks for all the info
badgermikeAuthor Commented:
Wait I have 300 GB disk sizes and 8 of them. When I build the raid before I noticed a 64KB stripe size.
If I mirror 2 of the disks then I would be using 600GB's on the ESX Install! That seems a bit wasteful.
If you mirror disks, you lose 1 disk of storage...so you have only 300GB. It's wasting 300GB yes, but it's redundancy of your data so if a disk fails, you don't lose your data...you have the 2nd disk in the mirrored RAID to protect you. It's really up to you as far as what the cost is to protect your data/VM storage.

Let me know if you have further questions.


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badgermikeAuthor Commented:
Thanks coolsport - I rather protect, I am going to give this a go now and get back to you.
Great...let me know how it goes...

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