strange hdparm results with serverworks and pata-serverworks
I have a ProLiant BL30p G1 machine running Debian Lenny (2.6.26 kernel).
It also has two identical, 2.5 inch WDC WD2500BEVE-00WZT0 IDE drives (new drives, no smart/badblock errors). Both drives are connected to a single IDE channel this machine has.
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Is there an explanation for that?
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 12 lines · Tomasz Chmielewski
I have a ProLiant BL30p G1 machine running Debian Lenny (2.6.26 kernel).
It also has two identical, 2.5 inch WDC WD2500BEVE-00WZT0 IDE drives (new drives, no smart/badblock errors). Both drives are connected to a single IDE channel this machine has.
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
Quoted 8 lines
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Is there an explanation for that?
Just a guess, but I would bet you have some sector remapping going on in the early portion of the 10/MB/sec drive.
Thus once dd gets based the area that has remapped sectors, it speeds up.
When reading the slow LBA sectors, the head is actually having to seek back and forth from the primary sector area out to the spares area. I've seen that before.
FYI: I saw a drive last week that had over 10% of the first 200 sectors bad. After that all was good. The drive I was looking at was several years old and remapping had not been triggered, so it was obvious what was going on when I ran dd to try and read the entire drive.
Greg
Signature · 9 lines
Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com
Quoted 12 lines · Greg Freemyer
Quoted 11 lines
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Quoted 8 lines
Just a guess, but I would bet you have some sector remapping going on in the early portion of the 10/MB/sec drive.
Thus once dd gets based the area that has remapped sectors, it speeds up.
When reading the slow LBA sectors, the head is actually having to seek back and forth from the primary sector area out to the spares area. I've seen that before.
There is some logic in this, but:
- smartctl doesn't show any remappings - AFAIK it should?
- there are some more of these HP ProLiant BL30p G1 blades here - some show this behaviour, some don't (i.e., both drives are as fast from the very beginning). Always the first drive shows this behaviour.
Could be an issue with these WDC WD2500BEVE-00WZT0 drives when they are connected as master? Why the issue doesn't show up on all such blades?
Quoted 5 lines
FYI: I saw a drive last week that had over 10% of the first 200 sectors bad. After that all was good. The drive I was looking at was several years old and remapping had not been triggered, so it was obvious what was going on when I ran dd to try and read the entire drive.
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 8 lines · Tomasz Chmielewski
I have a ProLiant BL30p G1 machine running Debian Lenny (2.6.26 kernel).
It also has two identical, 2.5 inch WDC WD2500BEVE-00WZT0 IDE drives (new drives, no smart/badblock errors). Both drives are connected to a single IDE channel this machine has.
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
Quoted 5 lines
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Is there an explanation for that?
..
Well, as you have shown, both hdparm and dd give the same results when doing (almost) the same test: the first 3 seconds are slow.
After that, I would assume that the kernel read-ahead algorithms kick in better and improve things.
But 10-20Mbytes/sec is slow for most modern drives, even for 2.5" drives. Older ones, sure, that's fine, but the newest 2.5" drives should score between 40 and 100Mbytes/sec.
The drive you listed is a WD 250GB mobile drive, PATA interface. I have a very similar WD drive here (WD2500BEAS) that regularly tops 60Mbytes/sec with "hdparm -t".
The difference could easily be in the chipset used to communicate with the drive. You said "serverworks" driver, and "pata-serverworks". The kernel start up logs will have more information, including the timing info chosen by libata.
Cheers
Quoted 11 lines · Mark Lord
Quoted 10 lines · Tomasz Chmielewski
I have a ProLiant BL30p G1 machine running Debian Lenny (2.6.26 kernel).
It also has two identical, 2.5 inch WDC WD2500BEVE-00WZT0 IDE drives (new drives, no smart/badblock errors). Both drives are connected to a single IDE channel this machine has.
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Quoted 7 lines
Quoted 3 lines
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Is there an explanation for that?
..
Well, as you have shown, both hdparm and dd give the same results when doing (almost) the same test: the first 3 seconds are slow.
But only for hda/sda. Not for hdb/sdb.
Quoted 7 lines
After that, I would assume that the kernel read-ahead algorithms kick in better and improve things.
But 10-20Mbytes/sec is slow for most modern drives, even for 2.5" drives. Older ones, sure, that's fine, but the newest 2.5" drives should score between 40 and 100Mbytes/sec.
BTW, I didn't mention it - these machine have CSB5 IDE controllers.
drivers/ata/pata_serverworks.c say there are two revisions of these controllers: one capable of UDMA 4, one capable of UDMA 5. I'm not sure what revision it is:
00:0f.1 IDE interface: Broadcom CSB5 IDE Controller (rev 93) (prog-if 8a [Master SecP PriP]) Subsystem: Broadcom CSB5 IDE Controller Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx- Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64 Region 0: I/O ports at 01f0 [size=8] Region 1: I/O ports at 03f4 [size=1] Region 2: I/O ports at 0170 [size=8] Region 3: I/O ports at 0374 [size=1] Region 4: I/O ports at 2000 [size=16] Kernel driver in use: Serverworks_IDE Kernel modules: serverworks
Either way, yes, it should be faster.
(...)
Quoted 2 lines
The difference could easily be in the chipset used to communicate with the drive.
Controller's chipset? That it has some extra doubts before it decides to read
"faster" from the first drive (master), but doesn't have these doubts when reading from the slave drive?
Quoted 3 lines
You said "serverworks" driver, and "pata-serverworks". The kernel start up logs will have more information, including the timing info chosen by libata.
Here is what 2.6.28.7 says:
[ 1.799408] ata1.00: ATA-8: WDC WD2500BEVE-00WZT0, 01.01A01, max UDMA/100 [ 1.799413] ata1.00: 488397168 sectors, multi 8: LBA48. [ 2.100115] ata1.01: ATA-8: WDC WD2500BEVE-00WZT0, 01.01A01, max UDMA/100 [ 2.100118] ata1.01: 488397168 sectors, multi 8: LBA48. [ 2.109007] ata1.00: configured for UDMA/100 [ 2.124554] ata1.01: configured for UDMA/100 [ 2.291564] scsi 0:0:0:0: Direct-Access ATA WDC WD2500BEVE-0 01.0 PQ: 0 ANSI: 5 [ 2.291761] scsi 0:0:1:0: Direct-Access ATA WDC WD2500BEVE-0 01.0 PQ: 0 ANSI: 5 [ 2.303851] Uniform Multi-Platform E-IDE driver [ 2.318650] Driver 'sd' needs updating - please use bus_type methods [ 2.318771] sd 0:0:0:0: [sda] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.318790] sd 0:0:0:0: [sda] Write Protect is off [ 2.318793] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.318822] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.318901] sd 0:0:0:0: [sda] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.318919] sd 0:0:0:0: [sda] Write Protect is off [ 2.318922] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.318951] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.318955] sda: sda1 sda2 sda3 [ 2.401158] sd 0:0:0:0: [sda] Attached SCSI disk [ 2.401225] sd 0:0:1:0: [sdb] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.401243] sd 0:0:1:0: [sdb] Write Protect is off [ 2.401246] sd 0:0:1:0: [sdb] Mode Sense: 00 3a 00 00 [ 2.401274] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.401332] sd 0:0:1:0: [sdb] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.401350] sd 0:0:1:0: [sdb] Write Protect is off [ 2.401353] sd 0:0:1:0: [sdb] Mode Sense: 00 3a 00 00 [ 2.401382] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.401385] sdb: sdb1 sdb2 [ 2.453608] sd 0:0:1:0: [sdb] Attached SCSI disk
And here's what Debian's 2.6.26 says:
[ 1.959553] Uniform Multi-Platform E-IDE driver [ 1.959553] ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx [ 1.983556] SvrWks CSB5: IDE controller (0x1166:0x0212 rev 0x93) at PCI slot 0000:00:0f.1 [ 1.983556] SvrWks CSB5: not 100% native mode: will probe irqs later [ 1.983556] ide0: BM-DMA at 0x2000-0x2007 [ 1.983556] ide1: BM-DMA at 0x2008-0x200f [ 1.983556] Probing IDE interface ide0... [ 2.270917] hda: WDC WD2500BEVE-00WZT0, ATA DISK drive [ 2.550916] hdb: WDC WD2500BEVE-00WZT0, ATA DISK drive [ 2.606710] hda: host max PIO4 wanted PIO255(auto-tune) selected PIO4 [ 2.606778] hda: UDMA/100 mode selected [ 2.606845] hdb: host max PIO4 wanted PIO255(auto-tune) selected PIO4 [ 2.606920] hdb: UDMA/100 mode selected [ 2.606983] Probing IDE interface ide1... [ 3.177157] ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 [ 3.177203] ide1 at 0x170-0x177,0x376 on irq 15 [ 4.313346] hda: max request size: 512KiB [ 4.369345] hda: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63 [ 4.369345] hda: cache flushes supported [ 4.369345] hda: hda1 hda2 hda3 [ 4.401458] hdb: max request size: 512KiB [ 4.693859] hdb: 488397168 sectors (250059 MB) w/8192KiB Cache, CHS=30401/255/63 [ 4.693859] hdb: cache flushes supported [ 4.693859] hdb: hdb1 hdb2
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 76 lines · Tomasz Chmielewski
Quoted 11 lines · Mark Lord
Quoted 10 lines · Tomasz Chmielewski
I have a ProLiant BL30p G1 machine running Debian Lenny (2.6.26 kernel).
It also has two identical, 2.5 inch WDC WD2500BEVE-00WZT0 IDE drives (new drives, no smart/badblock errors). Both drives are connected to a single IDE channel this machine has.
"hdparm -t" gives me different results for these drives: ~10 MB/s for hda, and ~20 MB/s for hdb with "serverworks" driver on Debian's 2.6.26 kernel. When using "pata-serverworks" with 2.6.28.7 kernel, hdparm shows the same results (~10 MB/s for sda, ~20 MB/s for sdb).
However, when I run "dd if=/dev/sda of=/dev/null bs=64k", I can see with iostat that for the first 7-8 seconds, reads are with ~10 MB/s speed. Then, reads from sda are with ~20 MB/s or more and are on par with sdb.
Quoted 7 lines
Quoted 3 lines
Similar dd test for sdb shows that it delivers with speed of ~20 MB/s from the first second.
Is there an explanation for that?
..
Well, as you have shown, both hdparm and dd give the same results when doing (almost) the same test: the first 3 seconds are slow.
But only for hda/sda. Not for hdb/sdb.
Quoted 7 lines
After that, I would assume that the kernel read-ahead algorithms kick in better and improve things.
But 10-20Mbytes/sec is slow for most modern drives, even for 2.5" drives. Older ones, sure, that's fine, but the newest 2.5" drives should score between 40 and 100Mbytes/sec.
BTW, I didn't mention it - these machine have CSB5 IDE controllers.
drivers/ata/pata_serverworks.csay there are two revisions of these controllers: one capable of UDMA 4, one capable of UDMA 5. I'm not sure what revision it is:00:0f.1 IDE interface: Broadcom CSB5 IDE Controller (rev 93) (prog-if 8a [Master SecP PriP]) Subsystem: Broadcom CSB5 IDE Controller Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx- Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64 Region 0: I/O ports at 01f0 [size=8] Region 1: I/O ports at 03f4 [size=1] Region 2: I/O ports at 0170 [size=8] Region 3: I/O ports at 0374 [size=1] Region 4: I/O ports at 2000 [size=16] Kernel driver in use:
Serverworks_IDEKernel modules: serverworks Either way, yes, it should be faster.(...)
Quoted 2 lines
The difference could easily be in the chipset used to communicate with the drive.
Controller's chipset? That it has some extra doubts before it decides to read
"faster" from the first drive (master), but doesn't have these doubts when reading from the slave drive?Quoted 3 lines
You said "serverworks" driver, and "pata-serverworks". The kernel start up logs will have more information, including the timing info chosen by libata.
Here is what 2.6.28.7 says:
[ 1.799408] ata1.00: ATA-8: WDC WD2500BEVE-00WZT0, 01.01A01, max UDMA/100 [ 1.799413] ata1.00: 488397168 sectors, multi 8: LBA48. [ 2.100115] ata1.01: ATA-8: WDC WD2500BEVE-00WZT0, 01.01A01, max UDMA/100 [ 2.100118] ata1.01: 488397168 sectors, multi 8: LBA48. [ 2.109007] ata1.00: configured for UDMA/100 [ 2.124554] ata1.01: configured for UDMA/100 [ 2.291564] scsi 0:0:0:0: Direct-Access ATA WDC WD2500BEVE-0 01.0 PQ: 0 ANSI: 5 [ 2.291761] scsi 0:0:1:0: Direct-Access ATA WDC WD2500BEVE-0 01.0 PQ: 0 ANSI: 5 [ 2.303851] Uniform Multi-Platform E-IDE driver [ 2.318650] Driver 'sd' needs updating - please use bus_type methods [ 2.318771] sd 0:0:0:0: [sda] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.318790] sd 0:0:0:0: [sda] Write Protect is off [ 2.318793] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.318822] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.318901] sd 0:0:0:0: [sda] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.318919] sd 0:0:0:0: [sda] Write Protect is off [ 2.318922] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.318951] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.318955] sda: sda1 sda2 sda3 [ 2.401158] sd 0:0:0:0: [sda] Attached SCSI disk [ 2.401225] sd 0:0:1:0: [sdb] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.401243] sd 0:0:1:0: [sdb] Write Protect is off
Quoted 8 lines
[ 2.401246] sd 0:0:1:0: [sdb] Mode Sense: 00 3a 00 00 [ 2.401274] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.401332] sd 0:0:1:0: [sdb] 488397168 512-byte hardware sectors: (250 GB/232 GiB) [ 2.401350] sd 0:0:1:0: [sdb] Write Protect is off [ 2.401353] sd 0:0:1:0: [sdb] Mode Sense: 00 3a 00 00 [ 2.401382] sd 0:0:1:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 2.401385] sdb: sdb1 sdb2 [ 2.453608] sd 0:0:1:0: [sdb] Attached SCSI disk
..
Everything looks configured correctly, so the only explanations for the slow (10/20MB/sec) speeds are the CPU/RAM, or other system activity.
As for the disparity in initial throughput between the master/slave drives, you could try reversing the two drives (swap them on the cable if using "cable select", otherwise rejumper the master/slave setup). Then see if the slow start follows the specific drive to its new position on the cable, or if the master ("a") drive is always slower.
Cheers
Quoted 2 lines · Mark Lord
Everything looks configured correctly, so the only explanations for the slow (10/20MB/sec) speeds are the CPU/RAM, or other system activity.
It's a pretty powerful machine with plenty of RAM, no other activity.
Quoted 5 lines
As for the disparity in initial throughput between the master/slave drives, you could try reversing the two drives (swap them on the cable if using "cable select", otherwise rejumper the master/slave setup). Then see if the slow start follows the specific drive to its new position on the cable, or if the master ("a") drive is always slower.
Yes, "reversing" the drives makes the master slower (at least initially).
Controller's "feature"?
Signature · 2 lines
Tomasz Chmielewski http://wpkg.org
Quoted 14 lines · Tomasz Chmielewski
Quoted 2 lines · Mark Lord
Everything looks configured correctly, so the only explanations for the slow (10/20MB/sec) speeds are the CPU/RAM, or other system activity.
It's a pretty powerful machine with plenty of RAM, no other activity.
Quoted 5 lines
As for the disparity in initial throughput between the master/slave drives, you could try reversing the two drives (swap them on the cable if using "cable select", otherwise rejumper the master/slave setup). Then see if the slow start follows the specific drive to its new position on the cable, or if the master ("a") drive is always slower.
Quoted 3 lines
Yes, "reversing" the drives makes the master slower (at least initially).
Controller's "feature"?
..
Kinda looks that way. Perhaps the driver isn't setting the master device up with optimal settings somewhere.. FIFO sizes or something ??
Maybe somebody more familiar with serverworks stuff could have a look now.