Performance problems:Did PE2850 ship with SCSI-2 backplane?
Dell at epperson.homelinux.net
Tue Sep 6 08:59:18 CDT 2011
On Tue, September 6, 2011 08:26, Brent Kimberley wrote:
> I have a question for the group. Does anyone know if PE2850 servers were
> shipped with a SCSI-2 backplane?
> This PE2850 was shipped from with the following options: a) N7108
> (Module, Information, Backplane 1X6, P2850); AND, b) T8677 (Assembly,
> Cable, Scsi, Backplane Riser, CHANNEL A...)
> I believe the machine has been crippled by a SCSI-2 backplane.
> If true, can anyone advise a simple way to work-around the issue?
> Perhaps jumper settings, cables, etc.?
> Has this happened to anyone else?
> Observations: - The system has been undergoing a slow/prolonged
> end-of-life failure for several years - The backplane reports SCSI-2 (i.e.
> 10MB/sec) - performance does not and did-not meet expectations * system
> yields 1 to 4 MB/sec for bulk sequential reads (i.e. dd bs=4MB
> if=/dev/<raw-SCSI-320-disk-array> of=/dev/null count=1000) * System
> should yield 40 to 240 MB/sec for bulk sequential reads * System performs
> worse during random access reads - system has low throughput / high
> latency (system should have high throughput / low latency as it was
> professionally configured & contains only OEM, enterprise, Ultra SCSI 320
> components) - unable to backup or archive in a timely fashion - system
> barely meets minimum "sunny-day" expectations when running contiguously
> for 8 to 18 hours per day.
Not normal. Here's a similar machine (although with a PERC):
[root at utility etc]# dmidecode|grep -i poweredge;lspci|grep RAID;dmesg|grep
-i model ;fdisk -l;dd bs=4MB if=/dev/sda3 of=/dev/null count=1000
Product Name: PowerEdge 2850
02:0e.0 RAID bus controller: Dell PowerEdge Expandable RAID controller 4
Vendor: PE/PV Model: 1x6 SCSI BP Rev: 1.0
Vendor: MegaRAID Model: LD 0 RAID5 419G Rev: 521X
Disk /dev/sda: 440.0 GB, 440087347200 bytes
255 heads, 63 sectors/track, 53504 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 4 32098+ de Dell Utility
/dev/sda2 * 5 69 522112+ 83 Linux
/dev/sda3 70 1101 8289540 82 Linux swap / Solaris
/dev/sda4 1102 53504 420927097+ f W95 Ext'd (LBA)
/dev/sda5 1102 8908 62709696 8e Linux LVM
/dev/sda6 8909 53504 358217338+ 83 Linux
1000+0 records in
1000+0 records out
4000000000 bytes (4.0 GB) copied, 30.6845 seconds, 130 MB/s
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