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0
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1answer
362 views

Can I set noatime for my XEN guest OS partition? Will it work?

I have a VPS in cloud environment based on XEN Virtualization platform. /etc/fstab looks like that: LABEL=PRGMRDISK1 / ext3 errors=remount-ro 0 0 As far as I know IO can pretty ...
3
votes
7answers
5k views

How do I tell which processes are writing heavily to disk in CentOS 5?

Our server started getting slow, so I ran iostat on it. iostat -dx 5 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 ...
6
votes
4answers
228 views

Frequently accessed files and I/O usage

I'm curious, from a performance standpoint, is there an advantage in storing all files in one directory versus having each file in a separate directory? I'm not concerned about organization. Also, ...
0
votes
2answers
149 views

What types of IO does SQL trace display?

Are they physical or logical IOs? If they're logical, is there a way to break it out similar to STATISTICS IO for a production server?
5
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1answer
1k views

Linux Read-Ahead Downsides

Hope all is well. I have a question regarding read-ahead caching. Are there any downsides to raising the size of the read-ahead cache? On our farm, we're currently running at 256, and upon raising ...
1
vote
2answers
930 views

Windows Disk I/O Analysis

It appears that we are having a problem with the disk i/o speed on our Windows 2003 Enterprise Edition server (64-bit). As we were initializing a database that created two 1G tablespaces on 3 ...
2
votes
1answer
3k views

Debugging IO Limitation

I have a Fedora box with some severe IO limitations which I have no idea how to debug. The server has a Areca Technology Corp. ARC-1130 12-Port PCI-X to SATA RAID Controller with 12 7200 RPM 1.5 TB ...
1
vote
2answers
512 views

I/O Reads and Writes per process Unix/SunOS?

Can prstat or something similar tell me how many reads/writes a process is doing similar to how Task Manager on Windows can show I/O Reads, I/O Writes and many other I/O columns per process? I'm ...
1
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2answers
1k views

lsass.exe high I/O with SQL Server 2005 sp3

Hi I have a SQL Server 2005 Enterprise Edition on a Windows Server 2003 Enterprise sp2. Lately, I get very high I/O(Reda, Write, Other in Task Manager) from process lsass.exe. When I run sysinternals' ...
6
votes
5answers
3k views

How to identify heavy write to disk?

I have this problem with server running CakePHP application. The server is insanely slow, I first thought that it's application problem, but then I found constant 5-6MB/s write to disk. What is the ...
0
votes
2answers
4k views

CPU or network I/O bound?

I'm trying to find out whether my server is network IO bound or CPU bound. I did look at the output of some of the typical tools to check the current status of the system (output of iostat, sar and ...
19
votes
3answers
14k views

Linux - How can I see what's waiting for disk IO

I have a server that has a really high load. Nothing is jumping out at me in terms of CPU usage, and it's not swapping. I think it's cause some processes are waiting for disk IO, and I want to see ...
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2answers
14k views

How can I monitor network I/O usage per process under Linux?

Such known tools like iftop/iptraf display network I/O per interface and per connection. Is there a way to see network I/O statistics per process?
2
votes
1answer
312 views

How to track cause of blocking IO problems

I move between multiple subnets and networks on a regular basis. I'm often faced with Explorer and other programs that stall in what appears to be an IO request. I'm trying to find a consistent way ...
1
vote
5answers
640 views

Expected throughput when re-building RAID array?

I'm just doing some testing on a NAS RAID array we've been lent to see if we want to deploy it. Just to see whats what, I decided to see what kind of network performance we get when it's re-building a ...
0
votes
4answers
270 views

Exchange 2003 I/O Troubles

We have some internal processes that send email to our Exchange 2003 system (on Win2K3 R2 32bit). Recently they have been intermittently failing with various errors -- boiled down they report ...
49
votes
6answers
36k views

Can anyone explain precisely what IOWait is?

As much as I have read about iowait, it is still mystery to me. I know it's the time spent by the CPU waiting for a IO operations to complete, but what kind of IO operations precisely? What I am also ...
14
votes
4answers
16k views

How to identify I/O bottlenecks on a Linux server?

How do you determine that the performance of your Linux server is I/O bound and, perhaps more importantly, what process or processes are casuing the problem?