Another Block size question

[dbrickman]

I just want to be clear on this. If I use 8MB block size for my data store it's not going to be wasting alot of space with all the 30K files within a VM? It's just going to allow me to create vmdk up to 2 TB.

Thanks,

Dan

[weinstein5]

It will allow you ot create a 2 TB vmdk -

[dbrickman]

Thanks, I understand that. What I want to know is if space is going to be taken up with all the files under 8 MB within a VM?

[beagle_jbl]

I know that you know that it will take up more space for small files and even for large files that arean't in increments of 8MB. However, this means VMWare files. It will have no effect on the space that the Guest OS files consume.

For example, your config files (vmx, vmxf) and log files that are stored with the VMDK files will all consume at least 8MB. It's a handful of files and in total will cost you AT MOST 60MB extra per virtual machine (over the default of 1MB). I am assuming that you aren't going to have too many VMs on this LUN so I am also assuming that 60MB is negligible.

I hope that answers your question??

[Dave_Mishchenko]

ESX can write multiple files to the same block so these small files could end up in one block - http://communities.vmware.com/thread/47171 / also page 2 here - http://www.vmware.com/pdf/vmfs_datasheet.pdf (see adaptive block sizing)

[beagle_jbl]

Good point and nice find.

Nonetheless, you will consume marginally more space.

[TomHowarth]

Welcome to the forums

I just want to be clear on this. If I use 8MB block size for my data store it's not going to be wasting alot of space with all the 30K files within a VM? It's just going to allow me to create vmdk up to 2 TB.

Thanks,

Dan

To answer your question, you are correct, Yes it will enable you to create a 2TB VMDK file. however VMFS is not like NTFS as it will fill up block space. Therefore, if you you have nine time 1MB files, you will not take up 72MB of disk space but you will only take up 9 MB. the remaining 7 MB in the second block will be filled up by other small files as and when required.

Tom Howarth

VMware Communities User Moderator

PS Drat - I see I was beaten by Dave again

[dbrickman]

Thanks, That's the answer I was looking for.