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Hello I have a 320 gb SATA 2 [wd3200aaks] on P4 2.66 with Mercury P4VM800M7 mobo
WHen I copy a movie in windows xp fat32 to fat 32, a programme called burst copy it shows speed of about 58 mbps [one partition to another]
when I copy same movie in pclinuxos 2007 (or debian4.0) i get speed of roughly 35 mbps, [XFS one partition to another XFS partition] why such a great difference in performance? and how can I speed up my harddisk under linux?
I have 2 gb ram
2 gb swap on same sata
no other harddisks
I have tested this number of times (and dont run any other software in between the copy process just to be sure of speed on both OS)
P.S does chosing syncronouse writting [all i/o/ synchronously] in XFS speed up the performance ? (because I think I had this feature unchecked (also if i check it will i get any performance penelty? and what its exact purpose btw, googled but didnt get something clearly )
If you are using Konqueror or Midnight Commander to measure the writing throughput, the bandwidth will worsen. I suggest use time with cp or mv to clock how fast or how long it will take. Then divide the type to the amount of bytes of the file. Any file system will have a bandwidth penalty when moving or copying data from one partition and then to the next partition. I suggest do the test with two hard drives on a different IDE channel or even better on a separate storage controller of the same model and brand.
On my notebook computer I get increase write and read performance using XFS compared to NTFS. Thanks to XFS buffering, I get more than 5 MB/sec compared to NTFS. My notebook computer has a Intel T7300 with 2 GB of DDR2.
My other computers also uses XFS and their throughput is high too. Again copying or moving data from partition to another partition cost performance.
I just play around with the format options.
The option async is faster than sync. The option sync will be slow because it tells the kernel and hard drive to flush cache to the medium. The async option will only flush the cache when the data has reached to a certain limit.
I tried using time, i get roughly same speed.
I am aware that If i copy data from one partition to another on same harddisk i face some performance penelty however I am tellling from my experience that in windows I was getting about 60 m/s from One partition partition to another on same harddisk ! how could it be while on linux i am getting virtuallly half of it
In copying between partitions on the same drive, the two big factors are:
1) How large are the chunks in which copying actually occurs. The OS may be buffering or caching to make the actual chunks larger than the chunks the copy program uses. In Linux, the dd program is available, which can copy in whatever chunk size you specify (subject to available memory).
2) How far apart are the partitions physically. Seek time is not linear with distance, but it does go up with distance. If I understood you correctly, four different partitions are involved: two for Windows and two for Linux. Maybe fdisk -l output would help us understand that aspect.
Sorry - got that all wrong.Thats what happens if you don't read the original post well.
First of all burstcopy uses RAM as buffer - wether that is a big factor depends on a lot of things.
Copy of oblivion.cab (1gb) ntfs->ntfs 42 sec with burstcopy
ntfs-> jfs 22 sec with Linux
In both cases that went from on disc to another with defragged M$ drives.
If you use partitions on the same disk or the drive is fragmented as hell I see how the buffer could speed up things a lot because it doesn't jump back and forth that much with an additional 64 mb or so buffer from ram.
Also disks are a lot slower the further the partition is to the inside of the platter because the relative speed is slower.
Last edited by crashmeister; 04-16-2008 at 09:14 AM.
burstcopy uses RAM as buffer - wether that is a big factor depends on a lot of things.
Sorry. I never heard of "burst copy" before reading the first post of this thread. I assume from its name it tries to do something intelligent regarding the buffer size. I have no idea what. But:
Any program copying from disk to disk uses ram as a buffer. How much ram it uses is usually a big factor.
Quote:
In both cases that went from on disc to another
But when going from one disk to another, the amount of ram isn't as big a factor as it would be from one partition to another on the same disk.
From one disk to another, it matters a lot whether something (OS or program) enables the overlap to start reading a second chunk before you're done reading the first. Given that overlap, even with unlimited ram, you wouldn't want the buffer to be a large fraction of the size of a large file.
With one disk and two partitions, you can't really start reading the second chunk before you're done writing the first. So with unlimited RAM, the fastest copy method would buffer the entire file in one chunk.
Quote:
it doesn't jump back and forth that much with an additional 64 mb or so buffer from ram.
When copying a big file between partitions on one disk on a system with 2gig of ram, I hope the software is smart enough to use a lot more than 64mb for buffering. (I don't know it is smart enough. I just hope).
Quote:
Also disks are a lot slower the further the partition is to the inside of the platter because the relative speed is slower.
I didn't know that. Do you happen to have a URL for hard facts on that effect? (I almost never have a URL for the facts I mention in threads like this, but if you happen to, I'd appreciate it).
Long ago, drives used lower physical density on outer tracks so the temporal density wouldn't change very much. Obviously, electronics have improved faster than disk surface quality has improved, so consistent physical density now should be more important than consistent temporal density. So the effect you describe should exist. I just wonder how big it is.
I didn't know that. Do you happen to have a URL for hard facts on that effect? (I almost never have a URL for the facts I mention in threads like this, but if you happen to, I'd appreciate it).
That any program uses RAM as a disk I/O buffer is new to me.Thats what they put buffers on the disks for.
Softwarebuffering generally isn't needed except with bad dvd burners that run out of data to burn and produce coasters.
What gets read ahead and back and forth and so on depends to large part on the interface (scsi,sata,whatever).
The density is the same all over the platter - htat it gets slower is just simple physics.
You got always the same rpm's - on the outside it is faster than on the inside.It is a disk after all.
in these tests , the pci ide bus mastering was enabled from bios.
I dual boot to windows/linux using GRUB (linux is pclinuxos 2007)
I have just noticed that If is Disable pci bus mastering it takes grub like 3 seconds FASTER to load in constast to when pci bus mastering is Enabled.Though the copying speed difference wasent noticeable in linux (wether bus mastering is enabled or disabled)
I thought it might help telling you this
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