6
votes
1answer
4 views

Writing to subfolder is faster than writing to its parent

I use dd to measure write perfomance and observed something strange: writing to /data/emzed2 is faster than writing to /data. This is the way I measured the performance: $ dd if=/dev/zero ...
2
votes
1answer
66 views

Optimal cluster size for random I/O

I'm specifically interested in the answer for NAND storage (SD cards, memory sticks). I have a Windows 7 laptop where I run 2 VM's inside VMWare, as well as multiple programs in the host OS. VM disk ...
4
votes
1answer
113 views

No performance increase on I/O intensive operation after symlink to ramdisk

We have a system that transforms a set of several thousand multi-MB files. After every step in the transform, it writes the intermediate file to disk. The concept is similar to a scratch disk. We ...
0
votes
1answer
300 views

<1MBps 4K read/write HDD issue

I bought a netbook, Windows Starter - it seemed really slow right from the start, so I removed all the bloatware, but it remained slow still. So I tested disk I/O with CrystalDiskMark and got 4k ...
3
votes
1answer
2k views

High Disk I/O and CPU usage of System Process in “System Volume Information”

I've a problem with high disk IO and cpu usage from the system process. With the performance monitor I can see that it writes and reads about 100MB/s froM "System Volume Information". I tried to get ...
0
votes
1answer
339 views

How to to measure and monitor I/O performance

We have a linux cluster with worker nodes sharing a common remote file system. We want to optimize the I/O, in particular when the workers read from the remote fs. The starting point is to measure ...
14
votes
4answers
45k views

Windows 8 extremely high disk usage and slow IO

Problem After upgrading from Windows 7 to Windows 8 Professional, there seem to be a few disturbing problems. When I have the Task Manager open, I sometimes notice the disk usage climbing to 50, ...
3
votes
1answer
989 views

Is it bad if millions of files are stored in one NTFS folder?

I have a very large NTFS volume with more than 20TB capacity and containing millions of files. If I put all of the files in the same folder, I know the performance is bad when I open the folder in ...
1
vote
1answer
788 views

How to avoid I/O bottlenecks in PC hardware selection and analysis?

I'm aware that the data transfer rate and the amount of memory held in the CPU cache can determine how fast a PC works. There are also probably a bunch of other factors that affect the performance of ...
2
votes
3answers
612 views

linux: accessing thousands of files in hash of directories

I would like to know what is the most efficient way of concurrently accessing thousands of files of a similar size in a modern Linux cluster of computers. I am carrying an indexing operation in each ...
0
votes
1answer
410 views

performance monitoring

I want to monitor CPU usage, disk read/write usage for a particular process, say ./myprocess. To monitor CPU top command seems to be a nice option and for read and write iotop seems to be a handy ...
6
votes
3answers
3k views

Debugging Linux I/O latency

I'm having some I/O problems on a couple of Linux systems that I administer. They manifest in that processes often block for up to several seconds in such simple syscalls as open(), unlink() or ...
3
votes
1answer
87 views

IO patterns during Explorer file copy

Copying several large files ( > 2GB ) between two USB HDDs reveals the I/O pattern below in Process Explorer. Write caching is disabled on the destination drive. I would have expected I/O to run at ...
3
votes
2answers
821 views

Slow performance during moderate/high IO

Windows XP machine suffering from slow performance during maintained IO, either network or disk. CPU & memory usage are both minimal, system+interrupts usage < 5% according Process Explorer. ...
3
votes
2answers
25 views

Is the XP VMM a bottleneck on a multi core machine?

I have a dual Xeon hex core machine running an IO intensive application. (WinXP 32) I am seeing a hardware driver (1/2 user mode, 1/2 kernel, streaming data) that is using 6k delta page faults per ...
1
vote
1answer
301 views

How do you monitor I/O on individual devices in windows?

Can anyone tell me if there's a handy little utility out there that will monitor and display the I/O charts for individual drives on windows? On linux Gkrellm is great for this.
19
votes
3answers
17k views

How to change I/O priority of a process or thread in Win7?

Process Explorer is able to show the effective IO priority of a given thread, but not change it. Seeing as IO priority support is a comparatively new feature, most programs don't set their own IO ...