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safe IOPS

 
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S. Boetticher
Regular Advisor

Re: safe IOPS

thx a lot.
so, the numbers from the table in your first post are 40% write, 60% read (they should include this important fact into the table)!

about fata/vr5:
can you also calculate our VTL EVA? EVA4400 with 96 1TB FATA in 1 DG, pure VR5.
according to the table at 40w/60r that should give 3264 IOPS, with backup blocksize 256KB would still give impressibe 816MB/s (we never saw that).
In order to reduce the load on the EVA with FATA and because our DB data is highly compressable we use HW-compression in the VTL, thus our EVA with FATA is still quick enough for our environment ;-)
Uwe Zessin
Honored Contributor

Re: safe IOPS

> Unfortunately this is a situation often found in customers
> as they use FATA disks for backup

But that is one (if not T-H-E) recommended use by HP!

The EVA6400/8400 quickspecs still points to this January 2006 paper:

""Please see the following URL for more information on FATA drives, their uses and their benefits:
http://h71028.www7.hp.com/ERC/downloads/5982-7353EN.pdf
""

One page 8:
""Tape drives continue to be an excellent choice for longer-term archiving data and longer-term security of data. However, with the availability of FATA disk storage users now have the option of using the lower cost FATA disks to stage backup, that is disk-to-disk backup, and then stage the lower cost copy of data to tape.""
.
Marcus Longardt
Advisor

Re: safe IOPS

I am glad that my thread can help someone.

Please tell me what's name of this Excel sheet is.

Thank you & regards
Marcus
V├нctor Cesp├│n
Honored Contributor

Re: safe IOPS

The 60% read, 40% write is often taken as a typical workload and used on the calculations. Of course the ratios can be very different.

I found a nice chart showing how SafeIOPs change in RAID 5 (attached)

For 96 x 1 TB FATA disks, with 40% writes I get 3,286 IOPS. Sequential write performace is usually calculated as 10 MB/s per drive, so you should be able to get those 800 MB/s.

----------------------------

In response to Uwe post above: yes, yes, FATA disks are meant to be used as backup. I was remarking that the number of available IOPS decreases with the number of writes and can be as low as 15 per drive when doing 100% writes on a RAID 5 vdisk (as is often the case).
Marcus Longardt
Advisor

Re: safe IOPS

Mmh - the graph shows me, that with 100% write the safeIOPS are the max IOPS.

Unfortunately the Hit % of sageIOPS are not 100% when max IOPS = Diskgroup IOPS!!

Then the Hit % is under 100%

Any ideas?
PB75
Advisor
Solution

Re: safe IOPS

HP did a official storage performance monitoring assessement in our environment (two EVA8100 with CA).
They used the formula on the attached JPG to calculate the SafeIOPS
Peter Mattei
Honored Contributor

Re: safe IOPS

Hi Marcus

You got some very good answers yet.
What about assigning some points to the posters?

Cheers
Pete
I love storage
Marcus Longardt
Advisor

Re: safe IOPS

@Pete:
Yes I have got a lot of answers, and I like this forum, because a lot of people are active on this board - but I don't think they do it for points!!

But to appease you, I submit the points a pair minutes before.

Regards
Marcus