?
Solved

Performance for RAID 5 SAS and HP 400i controller

Posted on 2013-05-24
6
Medium Priority
?
467 Views
Last Modified: 2013-05-27
Please verify whehter my assumption is correct or not.

With HP 400i controller, the thoughput is 3Gb/s -> max througput is 375MB/s

Each SAS RAID-5 hdd will have transfer rate ~ 140MB/s, so probably 3 HDDs may overload the controller but the card normal support more than that.

So, what do I miss ?

Tks
0
Comment
Question by:AXISHK
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
6 Comments
 
LVL 47

Assisted Solution

by:David
David earned 800 total points
ID: 39196028
real world with 3HDDs you won't get anything close to 375MB.  Don't worry about it.   Why? Because writes involve reading data from 2 disks and writing to 1.  Then you have to consider filesystem overhead and extra writes any other write requires for the filesystem.

You'll also never sustain 140MB/sec anyway, that is how fast data is read from cache.
0
 

Author Comment

by:AXISHK
ID: 39198329
Any material concerned with this type of calculation ? For HP 400i controller (thoughput ~ 375MB/s), what's max disk that it can support ?

Tks
0
 
LVL 56

Expert Comment

by:andyalder
ID: 39198841
Max disks a P400 supports is 18 in a ML370 G5 but that's really down to the number of drive bays available in the server. QuickSpecs also claim 38 disks but there isn't any server that takes that disk arrangement.

I don't know where you get "max througput is 375MB/s", 8*3Gb SAS lanes = 2.4GB/s although the PCIe bus is only 2GB/s.

It really depends what I/O pattern you throw at it though, your 15K disk may be able to read sequentially at 140MB/s so if you had a disk based backup system then you you may be able to stream from a 3 disk RAID 5 at something like 250MB/s but if your operating system is running on those 3 disks then it's not going to be sequential access. Worst case is about 200 IOPS, which means you can read 200 512 byte sectors in 1 second = 100 KBPS per 15K disk. There are some ballpark raw IOPS figures in http://en.wikipedia.org/wiki/IOPS.
0
Enterprise Mobility and BYOD For Dummies

Like “For Dummies” books, you can read this in whatever order you choose and learn about mobility and BYOD; and how to put a competitive mobile infrastructure in place. Developed for SMBs and large enterprises alike, you will find helpful use cases, planning, and implementation.

 

Author Comment

by:AXISHK
ID: 39198872
3Gbps  = 3,000,000,000 bps -> 3,000,000 kbps -> 375,000 kB/s -> 375 MB/s

Do you mean there are 8 lanes in P400i with 3Gb/s for each lane ?

Tks


http://h18000.www1.hp.com/products/quickspecs/12400_na/12400_na.html
0
 
LVL 56

Accepted Solution

by:
andyalder earned 1200 total points
ID: 39198936
Yes, there are 8 * 3Gb SAS lanes. In a simple 8 disk backplane configuration such as in a DL380 there is one lane per disk but the P400 also supports the SAS expander card that fans-out those 8 lanes into 24 lanes to allow 3 disk cages although the per-disk bandwidth is obviously less in that scenario.
0
 

Author Closing Comment

by:AXISHK
ID: 39198972
Tks
0

Featured Post

Prepare for your VMware VCP6-DCV exam.

Josh Coen and Jason Langer have prepared the latest edition of VCP study guide. Both authors have been working in the IT field for more than a decade, and both hold VMware certifications. This 163-page guide covers all 10 of the exam blueprint sections.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article explains how to install and use the NTBackup utility that comes with Windows Server.
In this article we will learn how to backup a VMware farm using Nakivo Backup & Replication. In this tutorial we will install the software on a Windows 2012 R2 Server.
This tutorial will walk an individual through locating and launching the BEUtility application to properly change the service account username and\or password in situation where it may be necessary or where the password has been inadvertently change…
This tutorial will walk an individual through configuring a drive on a Windows Server 2008 to perform shadow copies in order to quickly recover deleted files and folders. Click on Start and then select Computer to view the available drives on the se…
Suggested Courses

752 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question