Object Storage

 How does Hitachi storage work with operating systems?

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Data Conversion's profile image
Data Conversion posted 03-12-2018 14:46

I have a question about how storage works in Hitachi.

From a G1000 I have provisioned a server with a lun of 1 tb, the server used the lun for its operating system C: \ 100 gb and for D: \ the remaining gb which are not being used.But in the G1000 when reviewing the lun that was provisioned, it finds 100% use.There are some pdf or paper that explain this operation or that could be causing this behavior ?.Thank you very much for your answers.


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HALIL GUNDOGDU's profile image
HALIL GUNDOGDU posted 03-13-2018 16:07

Hi Jose,

What is your disk provision type, Dynamic Provision or not ? full allocation was checked ?

Also , if you get data this disk and than you were delete them and if your OS is not use "trim" options OS cant delete data physcaly in disk, only header pointers was deleted, so the storage is not know this operation, and your data still store in disk but without header so disk seen full from storage side. 

Data Conversion's profile image
Data Conversion posted 03-13-2018 19:18

Hi,

Thanks for you answer.

I think this is the case, my disk is dynamic provisioning. I was looking for documentation that explains this behavior but I could not find it, hitachi handles this information or is strictly at the OS level.

Nikita Afonin's profile image
Nikita Afonin posted 03-15-2018 06:27

Hi Jose,

There is Provisioning Guide for VSP G1x00 at Hitachi portal: https://knowledge.hds.com/@api/deki/files/29098/SVOS_v7_3_1_Provisioning_Guide_VSP_G1x00_F1500_MK-92RD8014-17.pdf?revision=1

You can find information about OS and filesystems on the pages 157-159.

fsandpool

Data Conversion's profile image
Data Conversion posted 03-15-2018 16:56

Hi Jose,

As Nikita points out, there is a huge difference in the way filesystems handle their formatting.

Most modern filesystems will only use and write to the portion of the disk they actually need to store data on, while others (mostly antiquated ones) will write blocks across the entire LUN when formatting.  This type of behaviour results in the storage being full capacity-wise to the array, despite thin-provisoining because the OS/Filesystem really did write data across the entire LUN.