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Usable Space in EVA

Sharjeel Saleem
Regular Advisor

Usable Space in EVA

HI,

Can any1 tell me if we are adding eight 300GB hard disk in different disk group, how much space we getting in usable space?

-Sharjeel
16 REPLIES
Patrick Terlisten
Honored Contributor

Re: Usable Space in EVA

Hello Sharjeel,

are the 8 disks member of a disk group? If yes, you need to ungroup those disks, and create a new DG with that disks.

Let's assume a new disk group with 8 disks and a protection level of "simple". You will get a usable capacity of round about 2,1 TB.

Best regards,
Patrick
Best regards,
Patrick
raadek
Honored Contributor

Re: Usable Space in EVA

Patrick,

Where did you take that number from?

HP StorageWorks Sizing Tool gives following figures:
100% VRAID5 -> 1440 GB usable
100% VRAID1 -> 900 GB usable
(8x 300GB, single protection,95% occupancy)

Rgds.
Don't panic! [THGTTG]
Patrick Terlisten
Honored Contributor

Re: Usable Space in EVA

Oh sorry, the 2,1 TB was only the usable capacity, which can be used to create vdisks.

8 disks x 300 GB - 300 GB (single protection) x 0,95 = 1,995 TB useable capacity.

Best regards,
Patrick
raadek
Honored Contributor

Re: Usable Space in EVA

Still it doesn't stack up - the maximum size of a vDisk you can create is 1440GB for vRAID5, or 1800GB for vRAID0 (which you really shouldn't be using for a production data ;-)
Don't panic! [THGTTG]
Uwe Zessin
Honored Contributor

Re: Usable Space in EVA

> 8 disks x 300 GB - 300 GB (single protection) x 0,95 = 1,995 TB useable capacity.

Assuming to configure a new disk group:
'Single protection' reserves 2x300GB (to be able to recover VRAID-1 data to new mirror pairs. Also, 300GB is the disk size in Hardware GigaBytes
(HWGB = 1,000,000,000) while the EVA displays Software GigaBytes
(SWGB = 1,073,741,824).

(8-2)*300/1.024/1.024/1.024 = 1676.380 SWGB

Subtract 5 to 10 SWGB to give the EVA some room for 'breathing' (5% is a waste in these days - check the latestest best practice guide).

VRAID-0: 1675 SWGB
VRAID-1: 837 SWGB
VRAID-5: 1340 SWGB


Sharjeel's question cannot be answered, because we don't know how the existing disk group is configured (size + number of disks, protection level).
.
Patrick Terlisten
Honored Contributor

Re: Usable Space in EVA

Moah... You're right, Uwe. It slipped my mind - single = double, double = quad.

Best regards,
Patrick
Best regards,
Patrick
Sharjeel Saleem
Regular Advisor

Re: Usable Space in EVA

Hi All,

Thx for valuable comments...but i didnt get HWGB & SWGB concept :(
Secondly the single protection is occupied 2 disk from the disk group then we didnt subtract 2 disk from the given formula,

8 disks x 300 GB - 300 GB (single protection) x 0,95 = 1,995 TB useable capacity.

UWE, there is 1 disk group configured in our EVA with single protection level.
Uwe Zessin
Honored Contributor

Re: Usable Space in EVA

> Thx for valuable comments...but i didnt get HWGB & SWGB concept :(

OK, I'll go a bit more in detail:

I'm sure you know the difference between decimal and binary.
We humans usually work with decimal numbers 1, 10, 100
A computer works binary: 1, 2, 4, ... 512, 1024, ...


I have an EVA with "300GB" disk drives. With the Storage System Scripting Utility (SSSU) I can find out how many blocks a disk drive has:
formattedcapacity ..: 585937500

Each block contains 512 bytes:

585,937,500 * 512 = 300,000,000,000


I divide it by 1,000,000,000 (=1000*1000*1000) and get: 300 GigaBytes

That is what is printed on the disk drive, so it is "HardWare GigaBytes (HWGB)".


Command View EVA divides it by 1,073,741,824 (=1024*1024*1024) and gets: 279.39648

which is pretty much what CV-EVA shows: 279.39


So, it is the same amount of data - just show differently, like:
5(10) = 101(2)
.
Sharjeel Saleem
Regular Advisor

Re: Usable Space in EVA

Thx! we can installed 300GB 15K harddisk in EVA4000?
Uwe Zessin
Honored Contributor

Re: Usable Space in EVA

Yes, you can. The EVA4000 did support 300GB disk drives since day one
(I have just checked version 1 of the specifications from May 2005).
.
Sharjeel Saleem
Regular Advisor

Re: Usable Space in EVA

Sure? because document we can installed only 10K 300GB??? thx
Uwe Zessin
Honored Contributor

Re: Usable Space in EVA

Sorry, missed the 15k - I was just thinking about the ability to deal with 300GB disks.
Is your EVA still at that old XCS firmware level?
.
Patrick Terlisten
Honored Contributor

Re: Usable Space in EVA

Hello,

300 GB 15K rpm dual-port 2/4 Gb/s FC-AL 1-inch drive AG425A

The 300GB/15k drives aren't listed in the quickspecs of a EVA4000, but they should work, also the 450 GB FC drives.

You should be sure that you're running XCS 6.110.

Best regards,
Patrick
Best regards,
Patrick
Uwe Zessin
Honored Contributor

Re: Usable Space in EVA

HP switched to an EVA-common specification file in February 2006. After that, but within 2006, support for 300GB 15kRPM disk drives became available.
I agree with Patrick that you should run with a current XCS release anyway.
.
Alain Charland
Occasional Visitor

Re: Usable Space in EVA

Usable and formated size are (as showed in CV-EVA)
279G*8 for the disk group=~2232G
A sigle protection will take 2*279G=~558G
You then have:~1674G
Raid 0 will take n * 1 of space
Raid 1 will take n * 2 of space
Raid 5 will take n * 1.25 of space
Thanks
Sharjeel Saleem
Regular Advisor

Re: Usable Space in EVA

Really appreciate about feedbacks...currently we are running XCS 6.0.

Thx