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15
votes
3answers
6k views

Is there a way to get Cache Hit/Miss ratios for block devices in Linux?

Is it possible to see in Linux how many read and write requests from user space end up causing cache hits and misses for block devices?
6
votes
6answers
7k views

Find the bottleneck: disk I/O on Windows XP

One of our development boxes has developed a problem wherein performance will occasionally drop through the floor. When this happens, you can hear the hard drive thrashing, but I don't know what's ...
5
votes
4answers
5k views

MySQL, disk I/O and SSD drives

We have a LAMP box with 2x mirrored 1 TB WD Black Caviar disks running the whole OS and MySQL. 8 GB / RAM, 2x quad core CPUs. We're really taxed on disk I/O, and I've been thinking of ...
5
votes
3answers
3k views

What program in Linux can measure I/O over time?

I'm trying to measure the total amount of disk writing and reading that is done to a particular volume by a particular process over a specified duration. I've found iotop, which can output IO every ...
4
votes
1answer
922 views

High disk time on SQL Server

We have a dedicated SQL Server 2008 R2 Enterprise Edition. The setup is: D: (data files) - stored on local ssd disks (not the same disks as log files) (raid 10) E: (log files) - stored on local ssd ...
3
votes
1answer
674 views

Possible disk IO issue

I've been trying to really figure out what my IOPS are on my DB server array and see if it's just too much. The array is four 72.6gb 15k rpm drives in RAID 5. To calculate IOPS for RAID 5 the ...
2
votes
4answers
3k views

How to reduce mysql disk io?

mysql> explain SELECT * -> FROM (`items`) -> WHERE `states` = 'A' -> ORDER BY `updated_date` desc -> LIMIT 20520, 40; ...
2
votes
2answers
1k views

Does a read on a NFS file system slow performance?

If a NFS client reads a file, does any network traffic happen? or is it just writes (by any node) that result in network traffic? In particular, I'm interested in whether doing a file_exists() call ...
2
votes
1answer
943 views

monitoring disk i/o via wmi

I'm using WMI to monitor Windows Server 2003 and Windows Server 2008 hosts. I got all the info I wanted but the disk I/O performance. I've tried quering the ...
1
vote
1answer
172 views

Disk IOs spikes at set times in CentOS

I recently installed Munin on my servers. Now 2 of my machines show big spikes in DiskIO at the same time, everyday at 4am. I run Centos 5.6 (64bit). I've checked my cron logs, and I have no personal ...
1
vote
3answers
1k views

Poor XFS performance — what's going on?

I recently formatted a 20TB array as XFS. For file transfers < 10G performance is fantastic. However once I exceed 10G disk I/O decays logarithmically. I have the journal on the same disk. When ...