1
vote
2answers
116 views

Why does dd show slow disk speed first time?

I'm checking the disk speed of a hdd on CentOS 6 using dd command. The setup is a DRBD setup - with this server being primary. To ensure that I get correct values, I execute the dd command 3 times ...
2
votes
0answers
86 views

mdadm raid10 or nfs performance issues?

I have a fresh mdadm RAID10 device which is healthy, built from 4 x 7200rpm SATA 3 drives: # cat /proc/mdstat Personalities : [raid10] [raid1] md2 : active raid10 sdc3[5] sda3[4] sdb3[1] sdd3[3] ...
2
votes
1answer
404 views

How to achieve multiple NFS/TCP connections to the same server?

I'm trying to maximize the NFS/TCP bandwidth between a Linux client and a single NFS server over a 10Gbps link. Although each NFS mount has its own device (major/minor), everything comes down to a ...
3
votes
1answer
111 views

Poor NFS Performance Using Multiple Disks

I have a server system running Ubuntu 12.10 with 12 disks attached. I am sharing all of these disks on my 10 gigabit network using NFSv4. However, I am getting generally poor performance over NFS ...
1
vote
1answer
556 views

KVM + NFS poor disk performance

Situation: We have an Ubuntu server that hosts three VMs using KVM. All guests as well as the host need to access the same files in a certain subfolder of /var . Thus, the subfolder is exported via ...
2
votes
4answers
2k views

Flush-0:n processes causing massive bottleneck

I have a LAMP cluster that shares files via NFS and occasionally one of them will be stricken for a while when mysterious flush processes start appearing. Can anyone help me? The only way to resolve ...
1
vote
2answers
2k views

Determining cause of high NFS/IO utilization without iotop

I have a server that is doing an NFSv4 export for user's home directories. There are roughly 25 users (mostly developers/analysts) and about 40 servers mounting the home directory export. ...
7
votes
2answers
2k views

Troubleshooting strategy for very poor iSCSI/NFS performance

We have a new Synology RS3412RPxs that offers iSCSI targets to three Windows 2008 R2 boxes and NFS to one OpenBSD 5.0 box. Logging into the RS3412 with ssh and reading/writing both small files and ...
1
vote
2answers
139 views

Does it make sense to copy files in parallel to the same NFS mount?

Here's an example: ( cp /tmp/one /nfs/one ) & ( cp /tmp/two /nfs/two ) & ( cp /tmp/three /nfs/three ) & ( cp /tmp/four /nfs/four ) & ( cp /tmp/five /nfs/five ) & wait Against a ...
3
votes
1answer
493 views

Poor NFS performance when sequentially reading large files

I have an NFS3 server with multiple clients. Each client is sequentially reading a different large file, and performance is very poor. Here is what I am observing in iostat on the server for the disk ...
0
votes
1answer
1k views

Measure & benchmark the speed & latency of file access on a mounted NFS share

I have a Linux Centos system that mounts some NFS shares, what technique can I use to measure the I/O speed/latency/rate when reading and writing files from that share? Could this technique also be ...
0
votes
3answers
1k views

Disk throughput dramatically reduced when using ZFS on OpenSolaris?

I'm building a simple ZFS file server for the small business I work for. The server is a Dell Poweredge 840, with 1GB RAM. The OS (OpenSolaris 2009.06) is installed on one SATA drive, and there are ...
2
votes
1answer
1k views

Reasons for an upgrade to NFS 4

I am trying to convince our sysadmins to upgrade from NFS 3 or NFS 4 because I think that this will result in a dramatically performance improvement, especially when dealing with many small files. ...
0
votes
4answers
216 views

NFS robustness or weaknesses

I have 2 web servers with a load balancer in front of them. They both have mounted a nfs share, so that they can share some common files, like images uploaded from the cms and some run time generated ...
3
votes
1answer
1k views

Weird nfs performance: 1 thread better than 8, 8 better than 2!

I'm trying to determine the cause of poor nfs performance between two Xen Virtual Machines (client & server) running on the same host. Specifically, the speed at which I can sequentially read a ...
1
vote
2answers
489 views

Linux NFS performance vs other FSs

It is expected that NFS will be slower than any "normal" file system such as EXT3. Transferring files over the network is the main reason for the additional delay. I am wondering how NFS can be ...
0
votes
3answers
254 views

Linux kernel multiple file system drivers and performance

I am not sure how Linux kernel handles multiple file system drivers and if an inode lookup for each given mounting point in file system interferes with other mounting points, or is there something ...
1
vote
2answers
1k views

Best practice with huge VM disks, NFS mount or huge image file?

I am looking into a backup solution, it will run on a virtual machine located at our KVM-host. The question is wether it is best to use a LVM-volume on the host and mount that with NFS into the guest ...
2
votes
2answers
836 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 ...
1
vote
1answer
584 views

Using a NAS to store user files over iSCSI/NFS?

I have an environment with servers (5-6) virtualized and hosted locally on the hypervisor. They act as file servers, so am thinking of moving the files out to a NAS (TheCUS or QNAP) and share over ...
1
vote
1answer
767 views

Very Slow Sequential Reads over NFS from an XFS disk in Amazon EC2

I am using tiobench to test performance of an NFS mounted volume, and notice that Sequential Reads are much slower than Random Reads. This isn't the behavior when I run the same test on the disk ...
18
votes
8answers
9k views

Analyzing Linux NFS server performance

I'd like to do some analysis of our NFS server to help track down potential bottlenecks in our applications. The server is running SUSE Enterprise Linux 10. The kind of things I'm looking to know ...
6
votes
7answers
8k views

Slow NFS transfer performance of small files

I'm using Openfiler 2.3 on an HP ML370 G5, Smart Array P400, SAS disks combined using RAID 1+0. I set up an NFS share from ext3 partition using Openfiler's web based configuration, and I succeeded to ...
1
vote
2answers
551 views

What are some good ways to monitor IO throughput and load from the client of an NFS share?

I have an ETL process that opens files from an NFS mount to process them. The number of files to be opened simultaneously is configurable. I don't have shell access to the NFS server. What are some ...