will 2 hdds improve performance?

[Shreekant]

Hi

This just struck me some time ago. It might be helpful in improving system response and overall performance. I'd like some opinions on this:

You know that an hdd ( no matter how fast ) can service only one request at a time. Now, an hdd read or write can happen in these cases
- an application writing/requesting some data
- os performing vitual memory swapping operations

Another fact related to virtual memory swapping is that the OS swaps out a process while the process has requested an hdd operation and is idle waiting for the response.

Here comes the quirky part. The swapping out operation is also actually an hdd write. So suppose a process in memory wants to write something into the hdd. In case of a SINGLE hdd system, what will happen is ..

1. the process in memory will issue an hdd write and will sit idle waiting for the response
2. the os detects that the process is idle, and hence tries to swap it out of memory.
3. the hdd does the write operation requested by the process
4. it then continues to swap out the process itself (which was absolutely unneccessary, since the hdd write request has been fulfilled now).
5. the swapped out process is swapped in at once, as it need not be idle any longer( its write request is fulfilled and has to carry on with other work).

The result is lots of unnecessary swap in-swap out operations, slowing down the system. The problem is caused because of steps 3 and 4 happening ONE AFTER THE OTHER.

In my view, any system with a single hdd will suffer from this problem.

One solution is to have two hard disks ( not two partitions, but physically separate ). The smaller one for EXCLUSIVE use by the OS and for SWAP SPACE. The other larger hdd for applications. This will allow the OS to perform swapping operations independently of the application data read/write operations. Now steps 3 & 4 will happen simultaneoulsy. The hdd for OS will handle the swapping task and the other hdd will service application data requests.

Is any one out there who has a similar hdd combination and has experienced SIGNIFICANT perfomance boost ?

--Shri

( One could argue that this topic be posted in the hardware section... )

 

[devilhead_satish]

RAID does improve performance and if you are using Intel's mobos then all the more better cos these guys give you a free software called Intel App Accelerator which increases the data transfer rate between the processor and the hard disks.

 

[anishcool]

Two SATA HDDs configured in RAID 0 do significantly improve performance.

If your considering investing, wait and go for SATA 2.

SATA adaptors are availble so you will not need to change your motherboard.

 

[Keith Sebastian]

It does improve performance. I have a 1.5gb swap file on my second hard disk which eliminates stutters in Flight Simulator 2004 when flying around complex sceneries and high AI traffic.

This is a MS recommended method to improve performance. Always good to move swap file to a non OS hard disk.

 

[Shreekant]

cool
will do that on my new pc

 

[medigit]

a bit off topic i guess but INTEL APPLICATION ACCELERATER is not present for INTEL 865 GBF original mobo.can anyone explain why.

 

[pradeep_chauhan]

The hardware (865)does not support the INTEL APPLICATION ACCELERATER concept

 

[Anu]

Some more info about RAID

RAID 0 (Default) -- Striped Disk Array with no Fault Tolerance: Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails then all data in the array is lost.

RAID 1 -- Mirrored Disk Array: Provides redundancy in case one of the two drives fail. Provides twice the read transaction rate of single disks and the same write transaction rate as single disks.

RAID-0 is a simple implementation called striping, where data is divided across multiple disks (or spindles). Data is broken down into blocks (128K default), and each block is written to a separate disk in sequential order. The workload is reduced for all disks, helping to accelerate data delivery.

Advantages


I/O performance is greatly improved by spreading the I/O load across multiple channels and drives.
Easy to implement
Disadvantages


No fault tolerance
The failure of one drive will result in all data in an array being lost.
Should not be used in mission critical environments.


RAID-1 is called disk mirroring, and is done to ensure data reliability or a high degree of fault tolerance. In a RAID 1 configuration, the RAID management software instructs the subsystem's controller to store data redundantly across a number of the drives (mirrored set) in the array. In other words, the same data is copied and stored on different disks, or mirrored, to help ensure that should a drive fail the data is available somewhere else within the array.

Advantages


Offers the customer data integrity by having the same data on two drives.
Ideal for applications where data integrity is of utmost importance. This is not data backup.
Disadvantages

Inefficient use of disk capacity
Has the highest overhead of all RAID types (100 percent).

Matrix RAID adds a twist to the traditional RAID-0 and RAID-1 storage configurations. It tries to solve one of the most common dilemmas which many have when setting up RAID in their home and work systems. The dilemma being, "Do I use RAID-0 for higher performance, and risk losing all my data in the event of a disk failure? Or, do I utilize RAID-1 for instant data backups, but lose half of my system's storage capacity?". It's a tough choice for anyone to make, speed versus stability.


Why would you want two separate RAID volumes on a pair of hard drives?
It's quite simple, really. You could setup a RAID-0 array as your primary RAID volume, which would hold your operating system and applications which require high-performance disk access, but would not require data replication. This RAID-0 array could also be used for things like temp files or scratch space. The data stored in the RAID-0 volume would see enhanced performance levels, but in the case of a drive failure, all of the data in this area of the RAID setup would be lost.
The rest of your storage space could be dedicated to a RAID-1 array for your important data. This data would automatically replicate over both hard drives, so if one of the drives failed, you would still have an exact working duplicate of your data. Thus, you get a mix of high-speed and stability without compromising either feature in any major way.

While Matrix RAID only supports two hard drives in a working environment, you can add a third SATA hard drive to act as a hot-spare drive. This disk can be used to re-build the RAID-1 mirror volume of a Matrix RAID in the case of a drive failure.

 

[rohanbee]

I have a sata hard drive and a normal hard drive. Till now i have not actually felt a difference.
Where if any will i feel the difference ?

 

[anishcool]

Hey Anu, did you actually write that post yourself ?

Or did you just Ctrl+C & Ctrl+V.

Just curious !

I have a sata hard drive and a normal hard drive. Till now i have not actually felt a difference.
Where if any will i feel the difference ?

I think you will only feel the difference when you fill up your SATA drive.

Why don't you install all the big games on the SATA drive and see ?

 

[Anu]

Good Idea

Hey i have typed it i was just even trying to practice and improve my typing skills anyways now i feel that ctrl+c and Ctrl+V from some place would be better..Thanx for your idea..Next time i will do that

 

[pradeep_chauhan]

The diffrence in throughput can be seen by using a sata drive. The first indication is that programs and windows take lesser time to load.

 

[progistheway]

RAID-0 will definitely increase performance and will overhaul the responsiveness of the system considering that hdd is the prime bottleneck in a computer. I have a system with 2 SATAs in striped array and I see about 40 % increase in read speeds and 25 % increase in write speeds.

 

[[flAsh]]

if u configure 2 IDE or SATA I or SATA II Hdds in RAID 0 they will increase the performance by upto 50%

AND if u really have money Go 4 2 SCSI disks in RAID 0 it will f**k off every thing in storage u heard about