I have 2 brand new Dell servers : a PE6800 and PE2800.
They both have a Perc4e/Di Raid controller, and on both boxes, the 6 x 146Gb U320 disks are configured in 3 Raid1 sets. (3 x 146Gb effective sizes)
Both servers are running Red Hat Enterprise Linux 4 AS, with the latest kernel and packages.
The PE6800 has 4 processors and 16Gb of Ram. THe PE2800 has 2 processors and 4Gb of Ram
When writing large files (or a large amount of data) to the disks, I've noticed big delays.
First test : I've created a couple of files of 1Gb, one file after the other.
In most cases, it took somewhere between 30 seconds and 1 minute to create a file. After x amount of files, I was seeing a delay peak ... for some reason it took more than 7 minutes to create a file. After that file, the speed went back to 3 minutes. (same results on both machines)
I've changed a couple of parameters :
After rebooting the server, it still took between 8 and 50 seconds to create a file, with a maximum peak of 3 minutes.
I would expect a new server to be fast. 8 seconds would be more normal than 1 minute. 7 minutes or even 3 minutes is not acceptable for a fast server that is not running anything...
The speed remains the same, no matter what the destination volume is (/dev/sda, /dev/sdb and /dev/sdc gave the same results), and I'm seeing similar results on both machines.
What can I do to troubleshoot and what can I do to solve the issue ?
A hdparm on all disks, on both servers, also produced the same results :
thanks
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How can I believe in God when just last week I got my tongue caught in the roller of an electric typewriter?
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They both have a Perc4e/Di Raid controller, and on both boxes, the 6 x 146Gb U320 disks are configured in 3 Raid1 sets. (3 x 146Gb effective sizes)
Both servers are running Red Hat Enterprise Linux 4 AS, with the latest kernel and packages.
The PE6800 has 4 processors and 16Gb of Ram. THe PE2800 has 2 processors and 4Gb of Ram
When writing large files (or a large amount of data) to the disks, I've noticed big delays.
First test : I've created a couple of files of 1Gb, one file after the other.
In most cases, it took somewhere between 30 seconds and 1 minute to create a file. After x amount of files, I was seeing a delay peak ... for some reason it took more than 7 minutes to create a file. After that file, the speed went back to 3 minutes. (same results on both machines)
I've changed a couple of parameters :
Code:
vm.dirty_expire_centisecs = 300
vm.dirty_writeback_centisecs = 60
vm.dirty_ratio = 10I would expect a new server to be fast. 8 seconds would be more normal than 1 minute. 7 minutes or even 3 minutes is not acceptable for a fast server that is not running anything...
The speed remains the same, no matter what the destination volume is (/dev/sda, /dev/sdb and /dev/sdc gave the same results), and I'm seeing similar results on both machines.
What can I do to troubleshoot and what can I do to solve the issue ?
A hdparm on all disks, on both servers, also produced the same results :
Code:
hdparm -T /dev/sda
/dev/sda:
Timing cached reads: 3492 MB in 2.00 seconds = 1744.52 MB/sec
hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 154 MB in 3.02 seconds = 50.93 MB/sec--------------------------------------------------------------------
How can I believe in God when just last week I got my tongue caught in the roller of an electric typewriter?
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