Checking for sequential write
Clash Royale CLAN TAG#URR8PPP
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I wrote(sequential) 10Gb data with transfer size of 64Kb to my external hard drive and used blktrace & blkparse to check whether these writes are 100% sequential or not.I used below command with %S to watch sequential view of writes.
blkparse sdX -f “%5T.%9t, %p, %C, %a, %d,%S, %Nn†-a complete –o output.txt
But my result is strange. Does anyone know why my result does not show sequential write? Can it be related to bad formating and mounting the disk in Linux?
linux performance
edited Jan 30 at 15:43
Weijun Zhou
1,434119
asked Jan 30 at 14:29
ati
12
add a comment |Â
up vote
0
down vote
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I wrote(sequential) 10Gb data with transfer size of 64Kb to my external hard drive and used blktrace & blkparse to check whether these writes are 100% sequential or not.I used below command with %S to watch sequential view of writes.
blkparse sdX -f “%5T.%9t, %p, %C, %a, %d,%S, %Nn†-a complete –o output.txt
But my result is strange. Does anyone know why my result does not show sequential write? Can it be related to bad formating and mounting the disk in Linux?
linux performance
edited Jan 30 at 15:43
Weijun Zhou
1,434119
asked Jan 30 at 14:29
ati
12
1
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13
add a comment |Â
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I wrote(sequential) 10Gb data with transfer size of 64Kb to my external hard drive and used blktrace & blkparse to check whether these writes are 100% sequential or not.I used below command with %S to watch sequential view of writes.
blkparse sdX -f “%5T.%9t, %p, %C, %a, %d,%S, %Nn†-a complete –o output.txt
But my result is strange. Does anyone know why my result does not show sequential write? Can it be related to bad formating and mounting the disk in Linux?
linux performance
edited Jan 30 at 15:43
Weijun Zhou
1,434119
asked Jan 30 at 14:29
ati
12
I wrote(sequential) 10Gb data with transfer size of 64Kb to my external hard drive and used blktrace & blkparse to check whether these writes are 100% sequential or not.I used below command with %S to watch sequential view of writes.
blkparse sdX -f “%5T.%9t, %p, %C, %a, %d,%S, %Nn†-a complete –o output.txt
But my result is strange. Does anyone know why my result does not show sequential write? Can it be related to bad formating and mounting the disk in Linux?
linux performance
edited Jan 30 at 15:43
Weijun Zhou
1,434119
asked Jan 30 at 14:29
ati
12
edited Jan 30 at 15:43
Weijun Zhou
1,434119
edited Jan 30 at 15:43
Weijun Zhou
1,434119
edited Jan 30 at 15:43
Weijun Zhou
1,434119
1,434119
asked Jan 30 at 14:29
ati
12
asked Jan 30 at 14:29
ati
12
asked Jan 30 at 14:29
ati
12
12
1
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13
add a comment |Â
1
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13
1
1
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13
add a comment |Â
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1
Does your external hard drive have a filesystem on it?
– Andy Dalton
Jan 30 at 15:07
Yes, I formatted with ext4. With other file systems like xfs and btrfs also the plot shows two separate lines! My expectation was a continuous line in the figure.
– ati
Jan 31 at 2:02
With a filesystem, you'll have to update the superblock eventually. The elevator algorithm also comes into play.
– Andy Dalton
Jan 31 at 14:34
@AndyDalton Would you please tell me, which option of ext4 formatting I should add to my command? In order to update the superblock.
– ati
Jan 31 at 14:40
You misunderstand. There's metadata on disk about what disk blocks are allocated. As the OS writes data, it'll update that metadata. I don't know the details of when, exactly, you'd expect that to happen.
– Andy Dalton
Jan 31 at 17:13