topic Re: Disk Space Available in Array Setup and Networking

Disk Space Available

hoangdv105 — Fri, 01 Aug 2014 07:51:46 GMT

I'm newbie Nimble and i have a question .

I have bought a pair nimble san 4 flash SSD (80gb/1 SSD) and 12 HDD (1T / 1 HDD) but when i connected nimble san which show 7.38TB available,

follow i know nimble use raid 6 to protect data, and just lost 2 disk so where data remaining ?? why just 7.38 TB available ??

and my nimble san like that

and where console port ???

Thanks,

Re: Disk Space Available

Nick_Dyer — Fri, 01 Aug 2014 14:58:53 GMT

Hello Hoang,

Sounds like you have a Nimble CS220, which as you said comes with 12x 1TB NL-SAS & 4x SSDs. The array runs RAID 6 (9 active drives, 2 parity & 1 dedicated hotspare). In our newly GA'd NimbleOS 2.1.4.0 we've changed to a Triple Parity RAID configuration for all systems in the field, which uses the hotspare as a third, dedicated parity drive. You lose no capacity or performance by implementing this new RAID set, but benefit by decreased rebuild times and extra protection for drive failures (look out for a blog post on this next week).

After RAID and other overheads a CS220 is advertised to return 8TB of usable storage prior to any data reduction. Now, In the world of marketing TB is the universal capacity measurement for storage. However in the real world we all know that a 1TB drive is never actually 1TB, it's usually somewhere around 920-940GB. This is because TB is calculated in multiples of 1000, but technically it should be calculated in multiples of 1024, which is called a Tebibyte (TiB for short).

Therefore in the Nimble UI we are actually reporting the usable capacity in TiB rather than TB. 8TB = 7.3TiB.

To answer your second question, you should have two "pig tail" cables in your Nimble shipment (look in the accessories box). The pig tail cable plugs into the wide, thin ports on each controller, and will provide you serial, VGA & USB breakout for each controller.

Hope this helps!

Re: Disk Space Available

hoangdv105 — Fri, 01 Aug 2014 15:16:37 GMT

Ya this very helpful for me, your answer made me understand my concern clearly.

And i will waiting for your blog post

Thanks very much.

Re: Disk Space Available

hoangdv105 — Fri, 08 Aug 2014 04:11:09 GMT

Hi Guy,

How about the 4x 80GB SSD? Do I need to add them to "flash pool" as NetApp storage or they were configured automatically?

Thanks so much

Re: Disk Space Available

Nick_Dyer — Fri, 08 Aug 2014 06:17:29 GMT

Hello Hoang,

There is no need to add them to a flash pool. The SSDs serve as a random read cache for hot blocks by default as part of the CASL architecture. The only configuration needed is whether you want a volume to use said caching or not. This is done within the Performance Policy (found in the "Manage" tab). Here you can ensure you don't pollute the cache by specifying that volumes such as SQL Log and Exchange Log bypass SSD as they are typically only written, but hardly read back. And as Nimble uses NVRAM & DRAM to accelerate writes, it means we can still provide high performance to those log file volumes.

HTH.

Re: Disk Space Available

hoangdv105 — Sun, 10 Aug 2014 17:19:37 GMT

Hi Nick,

Ok! Thank you for your answer.

HoangDV