Hi folks.
I'm posting this to both the Fedora as well as the CentOS lists in hopes that somewhere, someone can help me figure out what's going on. I have a dual Xeon 3GHz server that's performing rather slow when it comes to disk activities.
The machine is configured with a single 160 GiB OS drive (with CentOS 5.0) and 4x500 GiB drives setup in a RAID-5 configuration. All drives are setup for 3.0 GiB SATA link, and the motherboard also supports that. Looking in dmesg when the system comes up, I see that reflected as well:
ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata1.00: ATA-7, max UDMA/133, 312581808 sectors: LBA48 NCQ (depth 0/32) ata1.00: configured for UDMA/133 scsi1 : ahci ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata2.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32) ata2.00: configured for UDMA/133 scsi2 : ahci ata3: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata3.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32) ata3.00: configured for UDMA/133 scsi3 : ahci ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata4.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32) ata4.00: configured for UDMA/133 scsi4 : ahci ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) ata5.00: ATA-7, max UDMA/133, 976773168 sectors: LBA48 NCQ (depth 0/32) ata5.00: configured for UDMA/133 scsi5 : ahci
Now, I don't know what performance numbers *should* be, but on a 1.8 GiB copy on the RAID (cp from one location to another on the RAID), it gets done in just under 50 seconds. If I try to delete the folder afterwards (rm -rf FOLDER) it takes a few seconds to do so, however if I delete the CONTENTS of the folder, it does so within a fraction of a second (but then 'sync' takes a few seconds to catch up.)
That same folder that I'm copying contains 452 jpeg files in it, ranging from 2.5 to 6.2 MiB. Doing some image processing on them is where it takes a long time. At the moment I'm doing a simple thumbnail creation with the ImageMagick suite (convert FILE -thumbnail "200x200>' `basename FILE .jpg`.th.jpg) and it takes upwards of 8 minutes to complete. The whole time it's running, 'top' reports the server load as follows: load average: 1.06, 1.00, 0.81 And the CPU usage is around 9%.
Interestingly, if I run the same command and have it create .png instead, it takes longer, but I won't go there just yet. My question is, is this the expected performance on something like this, or should I be able to get better results? Is there something I should or could do to speed up disk based processes?
Or is this something where it's more memory intensive and I need to look at adding more (right now it has 2 GiB of memory.)
This problem is causing one of our web sites to time out because it's trying to process hundreds of image files and generate thumbnails, and it's taking forever to do that. So I'm starting at the bottom of the pile here, hardware. If it turns out the hardware is fine, and there's nothing else that can be done to speed it up, then I'll move forward to other possible culprits, such as the routines within the site scripts themselves...