Storage Best Practice

iSCSI related applications
Bellaichef
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Storage Best Practice

Postby Bellaichef » Mon Jun 11, 2018 11:23 pm

Hi all,

Fisrt of all I'm totally noob in storage, so sorry for all bull... I could write.
we recently own a TS-EC2480U.

We have a on it 12 x 5To hdd. We dedicated 2 disks for hot spare.
We created on all left hdds a Raid6 Volume.

The purpose of this NAS is to store disk dumps that are accessed from client machines. about 250 PCs can access these files at the same time.

To manage these dumps we use a windows 2k12 which access the storage via iSCSI (mutlipath) .

What is the best way to proceed ?:

-Create a big LUN (At least 45 To here) then access it through iSCSI.
Or
-Create Relatively "small" LUNS (Between 2 and 4To), access it via iSCSI and aggregate them in a single volume in Windows Disk Management.

Thanks by advance for your help.

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storageman
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Re: Storage Best Practice

Postby storageman » Mon Jun 11, 2018 11:28 pm

What's "To", I presume you mean TB
No, do not span LUNs in Windows, if one LUN goes offline you will lose everything.
One big LUN!

Bellaichef
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Re: Storage Best Practice

Postby Bellaichef » Tue Jun 12, 2018 3:43 am

Hi,

Thanks for your answer.

Yes by To I meant TB.
What do you mean by I'll loose everything?
I use LUNS for years now on Equallogic SAN ou QNAP NAS and till now I never lost a LUN. How could this happen when you do raid6 with 2 hotspare disk?
And in case I lose a LUN, why losing 1 big LUN with all my data would be less harmful than the lost of a LUN that would crash my LUN span?

Other question, regarding the perf, what is the best in speed performance?

regards,

Franck

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storageman
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Re: Storage Best Practice

Postby storageman » Tue Jun 12, 2018 3:51 pm

I'm not talking about the underlying RAID or the reliability of LUNs I'm talking about spanning in Windows.
Are you using span or stripe volume?
Striped volumes can corrupt files if one the LUNs in the stripe were to go offline.
Block is best for performance.

Bellaichef
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Re: Storage Best Practice

Postby Bellaichef » Wed Jun 13, 2018 2:11 am

First of all thanks for your advices.

I'm using span and not strip mode, which according to what i understood would be less dangerous than strip and a little bit less speedy than full block mode.
I'm waiting for a hdd pack which would allow me to transit from a mode to another.

I'll first bench both solutions to check if it worth it.

Regards

Franck

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storageman
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Re: Storage Best Practice

Postby storageman » Wed Jun 13, 2018 4:05 pm

Personally I would stick to 1 LUN, much easier to manage and make it block/thick. Just don't allocate all the storage pool, keep some space free in case the LUN fills up.

Do not use thin provisioning,it requires the reclaim job.


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