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Disk partitions for performance?

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June 7, 2010 9:05:49 AM

Hello,

is there any best practise these days for partitioning a HDD drive on a home PC system? Mostly in terms of disk performance.

I kind of "like" partitions and have by tradition created at least one operating system partition, one for the pagefile and one for data. It is no problem for me handling these different drive letters in terms of managability, but is there any gain performance wise in doing so? Or could it even be the opposite?

I am grateful for any advice on this topic.


EDIT: Changed thread from discussion to question.

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a c 415 G Storage
June 7, 2010 9:58:01 AM

You get better performance from the data which resides on the outermost tracks of the drive, since those tracks hold the most data and therefore have the fastest transfer rates and least head movement.

To get the best performance, create a partition on the drive only as large as you need and leave the rest unpartitioned - this will keep the data away from the slower inner tracks. The downside of this is that it's more difficult to deal with when you fill up the partition and want more space.

A school of thought recommends creating multiple partitions for various types of data, with the most frequently accessed ones occupying the outermost portion of the disk (ie, being the "first" partitions). The OS would typically be the first partition, possibly followed by a page file partition, then perhaps a scratch file partition, documents, archive files, etc. But this can backfire if your workload has to access files heavily in alternate partitions, since moving from one partition to another typically takes longer.

Personally I find that if you just use a single, whole-drive partition for each disk and then keep it well defragmented, you get pretty close to the same performance. To maximize performance and ease administration and backups I use two disks - one for the OS and one for everything else.
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June 7, 2010 10:07:44 AM

sminlal said:
You get better performance from the data which resides on the outermost tracks of the drive, since those tracks hold the most data and therefore have the fastest transfer rates and least head movement.


Thank you for your reply!

I have a few question regarding this, if you know:

Does the different tracks have different amount of sectors? (More on the edge and fewer inmost?)

As to the partition placement, how does this relate to a drive having multiple "disks" (I do not know the name. "Heads" a long time ago.) If the logical disk space stretches over several plates and on both sides of them, can you know where your data really is and optimize for that?

On a 1TB drive, is there any rule-of-thumb how large partition could be that would benefit from what you wrote above? Is there any approximate limit here?
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a b G Storage
June 7, 2010 12:05:18 PM

Here's what I did on my 750GB drive:

partition 1: appr 50-60GB (not in front of that computer now). OS, and a few of my most common programs - firefox, MS office.

partition 2: appr 250GB. Program files and other moderately used files

partition 3: remaining space. Misc storage for rarely used files. Larger downloads, VM storage.
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June 7, 2010 6:04:19 PM


Thanks for your reply!

I still wonder about the typical amount of plates in a harddrive and if both sides on each plate is typicaly used?

And if there could be found in the specifications for a drive how it is physicaly laid out? For example, if a 1TB drive perhaps has only one internal plate, but uses both sides, then perhaps the second half of the disk, around 500GB, would be the beginning on the other side. However that would asume that the tracks/cylinders has the same amount of sectors all the way in.

Without knowing this it could be quite hard to do an optimal partitioning of a drive. Or am I wrong about this totaly?
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a c 415 G Storage
June 7, 2010 8:52:03 PM

> Does the different tracks have different amount of sectors? (More on the edge and fewer inmost?)

Yes, modern drives pack more sectors around the outer tracks than around the inner ones to take advantage of the greater length available near the outer edge of the disk. Early hard drives didn't do this, but all modern ones have done it for around a decade or more.


> As to the partition placement, how does this relate to a drive having multiple "disks"

"Platters" is the word you're looking for. Disk drives are written cylinder-by-cylinder. In other words, when writing to a disk drive the data is written to all of the outermost tracks on the top and bottom of every platter first, then the heads are moved one "notch" inward and then all of the tracks accessible from that position are written, and so on. Discs are NOT written in platter order (like a vinyl LP record, for example).

So if you take a 1TB disk and partition it into two 500GB pieces, the first partition has the outer tracks of ALL the platters, and the second partition has all the inner tracks of ALL the platters. Since the outer tracks hold more data, the first partition will actually have fewer tracks in it than the second one - that means shorter seeks in addition to the faster transfer rates.


> On a 1TB drive, is there any rule-of-thumb how large partition could be that would benefit from what you wrote above?

The smaller you make the partition, the less seeking there will be to access the data and (if it's the first partition) the less slow-down in transfer rate there'll be since you're using the very fastest tracks. There isn't really a limit other than what you need to have terms of capacity.

But don't get overly excited. You're not going to see night-and-day performance differences, particularly if you put other partitions on the same drive as well. If you REALLY want to get good performance out of your system then think about using an SSD (Solid State Disk) for the Operating System. THAT will give you a HUGE boost in performance.
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a c 99 G Storage
June 7, 2010 11:44:43 PM

Quote:
I kind of "like" partitions and have by tradition created at least one operating system partition, one for the pagefile and one for data. It is no problem for me handling these different drive letters in terms of managability, but is there any gain performance wise in doing so? Or could it even be the opposite?


You would get better performance if you added a second (or third) drive to your system, rather than partioning up one drive. Partioning a single drive into several partions actually slows down your system, due to the multiple and wide range of read head movements. Swinging the read head to the outer, to the inner, back out, actually wears the drive more than just use it a one large single drive partion.

Yes, you can keep the partions defragmented easier, but as far as read/write speeds/access, it is slower.

I know this, having done much of the same in the past. I just gets tidious after a while! I used to break up a single drive into upto 6 partions (i.e 1-OS, 2-Program Files, 3-Internet cache/Temporary Files, 4-WinSwap/pagefile, 5-Documents, 6-Downloads, and 7-Set Up Files (copied install disks to hard drive), although maybe not is that order.

I found adding a second and third hard drive is more effecient. Now I have 3 drives: 1-OS & Program FIles (on a SSD!), 2-Data & Medie (My Documents, My Music, My Pictures, Videos, & Downloads), and 2-Back Up and Storage (of most everything automatically thru Windows, Norton or WinSync).

I found that I really like having my OS and Data files on seperate disk really conveinent. I can re-install/upgrade/update my OS, without losing any of my data. Then I drop & drag the folders from where WIndows puts them, to my 2nd drive.

And the OS drives can be small. Mine is 80GB total, only 46GB used. My Data/media disk is large (1TB), with my Back Up drive even larger (1TB).

That all being said, this all costs $$$ to get new drives. Then there a the size issue (e.g. Drive sizes are getting larger, where a smaller drive is actully more expensive ($/GB)).

Finally, like sminlal said, to get the best out of an OS drive, get a SSD. Then use your current disk as data/meia/backups.
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June 24, 2010 6:19:58 PM


I found adding a second and third hard drive is more effecient. Now I have 3 drives: 1-OS & Program FIles (on a SSD!), 2-Data & Medie (My Documents, My Music, My Pictures, Videos, & Downloads), and 2-Back Up and Storage (of most everything automatically thru Windows, Norton or WinSync).

I found that I really like having my OS and Data files on seperate disk really conveinent. I can re-install/upgrade/update my OS, without losing any of my data. Then I drop & drag the folders from where WIndows puts them, to my 2nd drive.

And the OS drives can be small. Mine is 80GB total, only 46GB used. My Data/media disk is large (1TB), with my Back Up drive even larger (1TB).

That all being said, this all costs $$$ to get new drives. Then there a the size issue (e.g. Drive sizes are getting larger, where a smaller drive is actully more expensive ($/GB)).

Finally, like sminlal said, to get the best out of an OS drive, get a SSD. Then use your current disk as data/meia/backups.[/quotemsg]



What about if you purchase a very large drive, like 2TB for example, and make 1 patition of 1TB and not even use the other partition? So the first 1TB of partition space will be extremely fast being on the outer edge, and the disk reader will never have to go to the inner most parts of the platter? Would this work in theory??
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June 25, 2010 9:22:39 AM

sminlal said:
> Does the different tracks have different amount of sectors? (More on the edge and fewer inmost?)

Yes, modern drives pack more sectors around the outer tracks than around the inner ones to take advantage of the greater length available near the outer edge of the disk.


Interesting! Do you know if this is the same with SCSI server harddisks?


sminlal said:
Disk drives are written cylinder-by-cylinder. In other words, when writing to a disk drive the data is written to all of the outermost tracks on the top and bottom of every platter first, then the heads are moved one "notch" inward and then all of the tracks accessible from that position are written, and so on. Discs are NOT written in platter order (like a vinyl LP record, for example).


This also explains a lot, and does indeed make it possible to make control the positioning of the partition to the other parts of the platters.

I wonder what the difference would be if I for example took a 1TB disk and divided it into four partitions, each 250 GB? If I copied files from a second disk, what could the performance difference be between the first and the fourth partition? If you would guess, is that 5%, 10% or 25%?

sminlal said:

If you REALLY want to get good performance out of your system then think about using an SSD (Solid State Disk) for the Operating System. THAT will give you a HUGE boost in performance.


Would that primarely be noticed in operating system start up? How much disk I/O could there really be on the OS disk during normal usage of a home PC after booting is completed?



foscooter said:

I found that I really like having my OS and Data files on seperate disk really conveinent. I can re-install/upgrade/update my OS, without losing any of my data. Then I drop & drag the folders from where WIndows puts them, to my 2nd drive.


Do you mean you can drag and drop folders like user profile and similar? It would be nice to move these kind of directories on to another physical drive, but I would have guessed that it required some other configuration.

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a c 415 G Storage
June 25, 2010 5:46:30 PM

TeaDrinker_OG said:
What about if you purchase a very large drive, like 2TB for example, and make 1 patition of 1TB and not even use the other partition? So the first 1TB of partition space will be extremely fast being on the outer edge, and the disk reader will never have to go to the inner most parts of the platter? Would this work in theory??

Yes, any time you partition down a drive and use only the first section of it, you'll see some performance improvement. But I'd hesitate to describe it as "extremely fast" compared to the rest of the drive. The outermost cylinders will typically have about twice as fast a transfer rate, but the access time will be only slightly faster. This is because access time consists of how quickly the heads move and how long it takes the platters to rotate, and these factors are exactly the same no matter whether you're accessing the innermost or outermost tracks. For the outermost tracks you only get a modest improvement in access time as a result of having more data packed onto fewer tracks, thus reducing the average amount of distance the heads have to move.

The the upshot is that partitioning the drive can substantially improve the average performance for tasks like copying files, but doesn't help very much at all for random I/O-intensive tasks like booting or starting applications.

Of course the trick is that in a lot of cases you won't notice much performance improvement unless you compare it against a disk that's pretty full. A disk that's fairly empty will often have most of the files located at the outermost tracks anyway.
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a c 415 G Storage
June 25, 2010 5:58:56 PM

ricno said:
Interesting! Do you know if this is the same with SCSI server harddisks?
Absolutely. It applies to all hard disk drives made in the last couple of decades (before that disks had the same number of sectors for all tracks because their controllers were much simpler).


> If I copied files from a second disk, what could the performance difference be between the first and the fourth partition? If you would guess, is that 5%, 10% or 25%?

See my previous post. You'll probably see transfer rates about twice as fast, but access times will be similar.


> Would that primarily be noticed in operating system start up? How much disk I/O could there really be on the OS disk during normal usage of a home PC after booting is completed?

SSDs give the most benefit when booting the system or when starting up a program (assuming the program is installed on the SSD). For a typical user who uses e-mail, office applications, and browsing that's almost all of the disk activity they ever do. Once a program is loaded and running, it typically does very little disk activity.

Certain programs, such as video editing and batch editing of photos, may do a lot of disk I/O while they run, and for those the SSD will likely be of less benefit aside from the initial load of the program. But they'll still be generally faster than a hard drive.



> Do you mean you can drag and drop folders like user profile and similar?

Moving the profile folders is a little tricky. Here's a link that describes how you could reconfigure windows to create new accounts with their profiles on another drive: http://www.windows7hacker.com/index.php/2009/05/how-to-...
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July 22, 2010 1:08:15 PM

Best answer selected by ricno.
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