All Questions
Tagged with performance dd
21 questions
0
votes
1
answer
45
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dd with 1M buffer is running at only 1 MB/s - disk usually can be accessed at full speed
I am running the command dd bs=1M if=/dev/zero of=/dev/md7 status=progress. It started very slow at 4 MB/s but now has dropped to 1 MB/s. This is a standard SATA disk that was running perfectly ...
- 101
2
votes
2
answers
68
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Recovery of a compressed image not possible due to lack of Space - general understanding of compression methods
I used gzip to compress an image which is quite huge still.
dd if=/dev/sda2 bs=1M | gzip -c -9 > sda2.dd.img.gz
then I changed the partitioning of the Drive because I wanted to install Linux.
And ...
1
vote
0
answers
326
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One particular UID causes very slow performance
One of our accounts on a CentOS 7 machine experienced very slow disk read/write.
I started looking into this because the 1007 user on this machine
ran wget much slower than other user/machines.
id
...
- 159
0
votes
2
answers
855
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Very low read speed from LTO6 tape in Linux CentOS
Dear technical experts,
For a number of weeks now I've been trying to extract data from an LTO6 tape without having too much success on the speed department.
I'm using 'dd' to dump the tape content ...
- 11
1
vote
0
answers
841
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How to test USB stick speed?
I have a USB stick I'm trying to measure the read and write speed on. I'm having trouble deciding whether I should write random data or zeros, and how much. I want to do this as fast as possible, ...
- 4,486
4
votes
3
answers
16k
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Why is dd so slow on a NVMe SSD?
I recently watched this video and in it, the author explains that a ram disk is far faster than HDD/SSD when using dd command. I understand why this is the case. What I don't understand, however, is ...
- 414
2
votes
1
answer
384
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Writing to EXT4 faster than writing to disk directly?
I tried to test the write speed of some SSDs and when writing to the disk directly is somehow slower that writing to the disk when it is formatted as ext4. How does this work? Is this correct or am I ...
- 55
1
vote
0
answers
698
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Alternatives to dd to read/write to a disk?
I'm using cp to read/write from an SSD drive but is not fast enough. Then I used dd, which is fast, especially with the drive unpartitioned. But I ran into errors like
there is no space left on ...
- 119
2
votes
0
answers
60
views
dd measurement question
I am wrestling with some perceived performance issues on a 3-node HPE Apollo cluster running Linux. (The cluster supports a backup application.) These are very $$ servers. In our setup each node ...
- 21
6
votes
1
answer
2k
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System lags when doing large R/W operations on external disks
I am having some issues with system-wide latency/lagging when doing large disk imaging operations on an Ubuntu 18.04 system. Here's the system specs:
Processor: Intel Core i7 (never near capacity on ...
- 109
3
votes
1
answer
5k
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Why is fio seq_writes so much faster than dd?
I have a zfs server, where I ran a couple of dumb tests just for understanding, and it puzzles me.
Context:- FreeBSD 11.2, ZFS with Compression enabled, SAS HDDs, RAIDz2, 768GB of memory.
Both ...
- 163
3
votes
1
answer
2k
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dd, ddrescue, dd_rescue performance according to OS (Ubuntu, macOS) [closed]
I put this question:
recover files from HSF+ USB External HD, test on CentOS 7 to diagnostic
And this
https://askubuntu.com/questions/955325/using-gpart-testdisk-to-recover-gpt-for-files-from-...
- 243
1
vote
2
answers
498
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optimum value for bs in 'dd' for chrooted linux?
I am trying to install chrooted debian (arm64) on my android phone(snapdragon650 & 3GB RAM). I found many tutorials for it.
Almost all the guides mentioned this cmd for creating img for chrooted ...
- 509
2
votes
2
answers
2k
views
Faster way to DD?
I am trying to DD a raw file to an SSD from a spin usb spin drive. I have tried compression (but it obviously has to expand before it can copy). I have watched the details of the arm7 gb ram device, ...
- 808
5
votes
2
answers
7k
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What is actually the speed reported by dd?
I always thought that when doing:
dd if=/dev/sdx of=/dev/sdy
the report which is displayed once the command finishes, such as:
79304319+0 records in
79304319+0 records out
40603811328 bytes (41 GB) ...
- 1,360