Solid state disk geometry

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Solid state disk geometry

Jens A. Griepentrog
Dear Mailing Listeners,

Let me know, please, whether it makes sense to modify disk geometry
for solid state disks? Which meaning have the default values of cylinders,
heads, and sectors for these devices? As an example, here are my sd1 data:

# fdisk sd1
Disk: sd1       geometry: 7783/255/63 [125045424 Sectors]
Offset: 0       Signature: 0xAA55
             Starting         Ending         LBA Info:
  #: id      C   H   S -      C   H   S [       start:        size ]
-------------------------------------------------------------------------------
  0: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
  1: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
  2: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
*3: A6      0   1   2 -   7782 254  63 [          64:   125033831 ] OpenBSD

Are there any disktab entries available more suitable for usual models
of solid state disks? At least it seemed reasonable to me to take multiples
of 64 blocks for the partition sizes and offsets:

# disklabel sd1
# /dev/rsd1c:
type: SCSI
disk: SCSI disk
label: SSDSA2SH064G1GC
duid: 78faa8282eb6f8fa
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 7783
total sectors: 125045424
boundstart: 64
boundend: 125033895
drivedata: 0

16 partitions:
#                size           offset  fstype [fsize bsize  cpg]
   a:          2097152               64  4.2BSD   2048 16384    1 # /
   b:         33554432          2097216    swap                   # none
   c:        125045424                0  unused
   d:         67108864         35651648  4.2BSD   2048 16384    1 # /home

To make things complete, here is the dmesg output after upgrading to 5.1.
Many thanks to the OpenBSD developers to keep the ball in play! Radeon
version xf86-video-ati-6.14.3 on ATI FirePro 2270 is a big progress;
it gives me a brillant digital image! Sometimes there are blackscreens
after switching back from X11 to console, which can be resolved by rebooting
the machine over network. Package qcad is missing but can be compiled easily
from the ports collection.

Best regards,
Jens

OpenBSD 5.1 (GENERIC.MP) #207: Sun Feb 12 09:42:14 MST 2012
[hidden email]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 17169842176 (16374MB)
avail mem = 16698621952 (15925MB)
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.6 @ 0xf06f0 (62 entries)
bios0: vendor American Megatrends Inc. version "0705" date 06/29/2010
bios0: ASUSTeK Computer INC. P7F-M WS
acpi0 at bios0: rev 2
acpi0: sleep states S0 S1 S3 S4 S5
acpi0: tables DSDT FACP APIC MCFG OEMB HPET SSDT
acpi0: wakeup devices BR1E(S4) UAR1(S4) PS2K(S4) PS2M(S4) EUSB(S4)
USB0(S4) USB1(S4) USB2(S4) USB3(S4) USBE(S4) USB4(S4) USB5(S4) USB6(S4)
BR21(S4) BR22(S4) BR23(S4) P0P1(S4) P0P3(S4) P0P4(S4) P0P5(S4) P0P6(S4)
USB8(S4) BR20(S4) BR24(S4) BR25(S4) BR26(S4) BR27(S4) PWRB(S4)
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel(R) Xeon(R) CPU L3426 @ 1.87GHz, 1867.02 MHz
cpu0:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF
cpu0: 256KB 64b/line 8-way L2 cache
cpu0: apic clock running at 133MHz
cpu1 at mainbus0: apid 2 (application processor)
cpu1: Intel(R) Xeon(R) CPU L3426 @ 1.87GHz, 1866.73 MHz
cpu1:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF
cpu1: 256KB 64b/line 8-way L2 cache
cpu2 at mainbus0: apid 4 (application processor)
cpu2: Intel(R) Xeon(R) CPU L3426 @ 1.87GHz, 1866.73 MHz
cpu2:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF
cpu2: 256KB 64b/line 8-way L2 cache
cpu3 at mainbus0: apid 6 (application processor)
cpu3: Intel(R) Xeon(R) CPU L3426 @ 1.87GHz, 1866.73 MHz
cpu3:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF
cpu3: 256KB 64b/line 8-way L2 cache
ioapic0 at mainbus0: apid 7 pa 0xfec00000, version 20, 24 pins
ioapic0: misconfigured as apic 1, remapped to apid 7
acpimcfg0 at acpi0 addr 0xe0000000, bus 0-255
acpihpet0 at acpi0: 14318179 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
acpiprt1 at acpi0: bus 7 (BR1E)
acpiprt2 at acpi0: bus -1 (BR21)
acpiprt3 at acpi0: bus -1 (BR22)
acpiprt4 at acpi0: bus -1 (BR23)
acpiprt5 at acpi0: bus -1 (P0P1)
acpiprt6 at acpi0: bus 1 (P0P3)
acpiprt7 at acpi0: bus -1 (P0P4)
acpiprt8 at acpi0: bus -1 (P0P5)
acpiprt9 at acpi0: bus -1 (P0P6)
acpiprt10 at acpi0: bus 2 (BR20)
acpiprt11 at acpi0: bus 5 (BR26)
acpiprt12 at acpi0: bus 6 (BR27)
acpicpu0 at acpi0: C3, C3, C1, PSS
acpicpu1 at acpi0: C3, C3, C1, PSS
acpicpu2 at acpi0: C3, C3, C1, PSS
acpicpu3 at acpi0: C3, C3, C1, PSS
acpibtn0 at acpi0: PWRB
ipmi at mainbus0 not configured
cpu0: Enhanced SpeedStep 1866 MHz: speeds: 1868, 1867, 1733, 1600, 1467,
1333, 1200 MHz
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "Intel Core DMI" rev 0x11
ppb0 at pci0 dev 3 function 0 "Intel Core PCIE" rev 0x11: msi
pci1 at ppb0 bus 1
vga1 at pci1 dev 0 function 0 vendor "ATI", unknown product 0x68f2 rev 0x00
wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
azalia0 at pci1 dev 0 function 1 "ATI Radeon HD 5470 Audio" rev 0x00: msi
azalia0: no supported codecs
"Intel Core Management" rev 0x11 at pci0 dev 8 function 0 not configured
"Intel Core Scratch" rev 0x11 at pci0 dev 8 function 1 not configured
"Intel Core Control" rev 0x11 at pci0 dev 8 function 2 not configured
"Intel Core Misc" rev 0x11 at pci0 dev 8 function 3 not configured
"Intel Core QPI Link" rev 0x11 at pci0 dev 16 function 0 not configured
"Intel Core QPI Routing" rev 0x11 at pci0 dev 16 function 1 not configured
ehci0 at pci0 dev 26 function 0 "Intel 3400 USB" rev 0x05: apic 7 int 16
usb0 at ehci0: USB revision 2.0
uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
azalia1 at pci0 dev 27 function 0 "Intel 3400 HD Audio" rev 0x05: msi
azalia1: no HD-Audio codecs
ppb1 at pci0 dev 28 function 0 "Intel 3400 PCIE" rev 0x05: msi
pci2 at ppb1 bus 2
em0 at pci2 dev 0 function 0 "Intel PRO/1000 PT (82575EB)" rev 0x02:
msi, address 00:25:90:0f:20:d0
em1 at pci2 dev 0 function 1 "Intel PRO/1000 PT (82575EB)" rev 0x02:
msi, address 00:25:90:0f:20:d1
ppb2 at pci0 dev 28 function 4 "Intel 3400 PCIE" rev 0x05
pci3 at ppb2 bus 3
ppb3 at pci0 dev 28 function 5 "Intel 3400 PCIE" rev 0x05
pci4 at ppb3 bus 4
ppb4 at pci0 dev 28 function 6 "Intel 3400 PCIE" rev 0x05
pci5 at ppb4 bus 5
em2 at pci5 dev 0 function 0 "Intel PRO/1000 MT (82574L)" rev 0x00: msi,
address bc:ae:c5:05:5b:71
ppb5 at pci0 dev 28 function 7 "Intel 3400 PCIE" rev 0x05
pci6 at ppb5 bus 6
em3 at pci6 dev 0 function 0 "Intel PRO/1000 MT (82574L)" rev 0x00: msi,
address bc:ae:c5:05:5b:b1
ehci1 at pci0 dev 29 function 0 "Intel 3400 USB" rev 0x05: apic 7 int 23
usb1 at ehci1: USB revision 2.0
uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1
ppb6 at pci0 dev 30 function 0 "Intel 82801BA Hub-to-PCI" rev 0xa5
pci7 at ppb6 bus 7
ahc0 at pci7 dev 2 function 0 vendor "Adaptec", unknown product 0x0082
rev 0x02: apic 7 int 21
scsibus0 at ahc0: 8 targets, initiator 7
sd0 at scsibus0 targ 6 lun 0: <FUJITSU, MCJ3230SS, 0010> SCSI2 0/direct
removable
pcib0 at pci0 dev 31 function 0 "Intel 3420 LPC" rev 0x05
ahci0 at pci0 dev 31 function 2 "Intel 3400 AHCI" rev 0x05: msi, AHCI 1.3
scsibus1 at ahci0: 32 targets
sd1 at scsibus1 targ 0 lun 0: <ATA, SSDSA2SH064G1GC, 045C> SCSI3
0/direct fixed naa.5001517959470944
sd1: 61057MB, 512 bytes/sector, 125045424 sectors
sd2 at scsibus1 targ 1 lun 0: <ATA, SSDSA2SH032G1GN, 045C> SCSI3
0/direct fixed naa.50015179594773ba
sd2: 30517MB, 512 bytes/sector, 62500000 sectors
cd0 at scsibus1 targ 5 lun 0: <Optiarc, DVD RW AD-7260S, 1.00> ATAPI
5/cdrom removable
ichiic0 at pci0 dev 31 function 3 "Intel 3400 SMBus" rev 0x05: apic 7
int 18
iic0 at ichiic0
sdtemp0 at iic0 addr 0x18: stts424e02
sdtemp1 at iic0 addr 0x19: stts2002
sdtemp2 at iic0 addr 0x1a: stts424e02
sdtemp3 at iic0 addr 0x1b: stts2002
spdmem0 at iic0 addr 0x50: 4GB DDR3 SDRAM registered ECC PC3-10600 with
thermal sensor
spdmem1 at iic0 addr 0x51: 4GB DDR3 SDRAM registered ECC PC3-10600 with
thermal sensor
spdmem2 at iic0 addr 0x52: 4GB DDR3 SDRAM registered ECC PC3-10600 with
thermal sensor
spdmem3 at iic0 addr 0x53: 4GB DDR3 SDRAM registered ECC PC3-10600 with
thermal sensor
isa0 at pcib0
isadma0 at isa0
com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo
pckbc0 at isa0 port 0x60/5
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
lm0 at isa0 port 0x290/8: W83627DHG
mtrr: Pentium Pro MTRR support
ahc0: target 6 synchronous at 20.0MHz, offset = 0xf
uhub2 at uhub0 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2
uhub3 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2
uhidev0 at uhub3 port 2 configuration 1 interface 0 "Logitech Optical
USB Mouse" rev 2.00/3.40 addr 3
uhidev0: iclass 3/1
ums0 at uhidev0: 3 buttons, Z dir
wsmouse0 at ums0 mux 0
vscsi0 at root
scsibus2 at vscsi0: 256 targets
softraid0 at root
scsibus3 at softraid0: 256 targets
root on sd1a (78faa8282eb6f8fa.a) swap on sd1b dump on sd1b

hw.sensors.cpu0.temp0=58.00 degC
hw.sensors.cpu1.temp0=58.00 degC
hw.sensors.cpu2.temp0=58.00 degC
hw.sensors.cpu3.temp0=58.00 degC
hw.sensors.sdtemp0.temp0=36.50 degC
hw.sensors.sdtemp1.temp0=33.00 degC
hw.sensors.sdtemp2.temp0=36.25 degC
hw.sensors.sdtemp3.temp0=37.00 degC
hw.sensors.lm0.temp0=24.00 degC
hw.sensors.lm0.temp1=24.50 degC
hw.sensors.lm0.temp2=26.00 degC
hw.sensors.lm0.fan0=1371 RPM
hw.sensors.lm0.fan1=1147 RPM
hw.sensors.lm0.fan2=1406 RPM
hw.sensors.lm0.volt0=0.90 VDC (VCore)
hw.sensors.lm0.volt1=11.40 VDC (+12V)
hw.sensors.lm0.volt2=3.36 VDC (+3.3V)
hw.sensors.lm0.volt3=3.36 VDC (+3.3V)
hw.sensors.lm0.volt4=-6.66 VDC (-12V)
hw.sensors.lm0.volt5=1.66 VDC
hw.sensors.lm0.volt6=1.49 VDC
hw.sensors.lm0.volt7=3.33 VDC (3.3VSB)
hw.sensors.lm0.volt8=1.62 VDC (VBAT)

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Re: Solid state disk geometry

Nick Holland
On 06/11/12 19:25, Jens A. Griepentrog wrote:
> Dear Mailing Listeners,
>
> Let me know, please, whether it makes sense to modify disk geometry
> for solid state disks?

no

> Which meaning have the default values of cylinders,
> heads, and sectors for these devices?

roughly the exact same thing it has meant for IDE, SATA, and SCSI disks
since..well...about 20 years or so...not a thing.

All modern drives, and really anything made in probably the last 20
years (i.e., anything worth putting on an OpenBSD machine) use
translation...the "geometry" and "reality" are unrelated in any
recognizable way.

> As an example, here are my sd1 data:
>
> # fdisk sd1
> Disk: sd1       geometry: 7783/255/63 [125045424 Sectors]
> Offset: 0       Signature: 0xAA55
>              Starting         Ending         LBA Info:
>   #: id      C   H   S -      C   H   S [       start:        size ]
> -------------------------------------------------------------------------------
>   0: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
>   1: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
>   2: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
> *3: A6      0   1   2 -   7782 254  63 [          64:   125033831 ] OpenBSD
>
> Are there any disktab entries available more suitable for usual models
> of solid state disks? At least it seemed reasonable to me to take multiples
> of 64 blocks for the partition sizes and offsets:

which, you will notice, is what OpenBSD does now.

If you knew what physical block size your SSD worked with, you might --
MIGHT -- see some benefit using that, but the 4k offsets seem to work
just fine.  I doubt you would feel any difference...

>
> # disklabel sd1
> # /dev/rsd1c:
> type: SCSI
> disk: SCSI disk
> label: SSDSA2SH064G1GC
> duid: 78faa8282eb6f8fa
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 255
> sectors/cylinder: 16065
> cylinders: 7783
> total sectors: 125045424
> boundstart: 64
> boundend: 125033895
> drivedata: 0
>
> 16 partitions:
> #                size           offset  fstype [fsize bsize  cpg]
>    a:          2097152               64  4.2BSD   2048 16384    1 # /
>    b:         33554432          2097216    swap                   # none
>    c:        125045424                0  unused
>    d:         67108864         35651648  4.2BSD   2048 16384    1 # /home
>
> To make things complete, here is the dmesg output after upgrading to 5.1.
> Many thanks to the OpenBSD developers to keep the ball in play! Radeon
> version xf86-video-ati-6.14.3 on ATI FirePro 2270 is a big progress;
> it gives me a brillant digital image! Sometimes there are blackscreens
> after switching back from X11 to console, which can be resolved by rebooting
> the machine over network. Package qcad is missing but can be compiled easily
> from the ports collection.
>
> Best regards,
> Jens
>
...
> ahc0 at pci7 dev 2 function 0 vendor "Adaptec", unknown product 0x0082
> rev 0x02: apic 7 int 21
> scsibus0 at ahc0: 8 targets, initiator 7
> sd0 at scsibus0 targ 6 lun 0: <FUJITSU, MCJ3230SS, 0010> SCSI2 0/direct
> removable

holy cow.  haven't seen one of those in a machine in a while. :)
(ok, actually, I don't think I've ever seen one, period.  Or maybe I've
got one...)
...

Nick.

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Re: Solid state disk geometry

Nico Kadel-Garcia-2
On Mon, Jun 11, 2012 at 8:05 PM, Nick Holland
<[hidden email]>wrote:

> On 06/11/12 19:25, Jens A. Griepentrog wrote:
> > Dear Mailing Listeners,
> >
> > Let me know, please, whether it makes sense to modify disk geometry
> > for solid state disks?
>
> no
>
> > Which meaning have the default values of cylinders,
> > heads, and sectors for these devices?
>
> roughly the exact same thing it has meant for IDE, SATA, and SCSI disks
> since..well...about 20 years or so...not a thing.
>
> All modern drives, and really anything made in probably the last 20
> years (i.e., anything worth putting on an OpenBSD machine) use
> translation...the "geometry" and "reality" are unrelated in any
> recognizable way.
>
Like many such generalizations, ignoring the details can cause catastrophic
failures. If your systems are virtualized, particularly virtualized on
NetApps which use 4096 byte block drives on the back end, that "translation
layer" can be overwhelmed. In particular, the use of the classic "msdos
compatibility" and the 63 blocks of 512 bytes typically assigned for MBR
and parttition can have a disastrous impact, which is tied to an old, old
standard for boot loaders and partition information.

Whether or not OpenBSD uses such an alignment structure, ignoring it by
aying "oh, we just translate" and "we've ignored that for decads" can cause
catastrophic slowdowns of the NetApp when the buffer on the NetApp used for
translation overflows and the NetApp goes into single CPU mode.

The white paper on the problem is  here:

http://www.citrix.com/site/resources/dynamic/partnerDocs/BestPracticesforFileSystemAlignmentinVirtualEnvironments.pdf

The burden is not as catastrophic on a local drive with a sane local
controller, but that re-alignment is still an unnecessary performance hit
that should be avoided in any high performance system.

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Re: Solid state disk geometry

Peter Laufenberg
In reply to this post by Nick Holland
>On 06/11/12 19:25, Jens A. Griepentrog wrote:
>> Let me know, please, whether it makes sense to modify disk geometry
>> for solid state disks?
>
>If you knew what physical block size your SSD worked with, you might --
>MIGHT -- see some benefit using that, but the 4k offsets seem to work
>just fine.  I doubt you would feel any difference...

Intel's answer about X25 SSDs' erase block size on their support forums is pretty much "fuck off".

-- p

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Re: Solid state disk geometry

Stuart Henderson
On 2012-06-12, Peter Laufenberg <[hidden email]> wrote:
>>On 06/11/12 19:25, Jens A. Griepentrog wrote:
>>> Let me know, please, whether it makes sense to modify disk geometry
>>> for solid state disks?
>>
>>If you knew what physical block size your SSD worked with, you might --
>>MIGHT -- see some benefit using that, but the 4k offsets seem to work
>>just fine.  I doubt you would feel any difference...
>
> Intel's answer about X25 SSDs' erase block size on their support forums is pretty much "fuck off".

Some SSD controllers use compression, so even if you have details
of flash block sizes you can't make any calculations about partition
alignment based on them.

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Re: Solid state disk geometry

Peter Laufenberg
>On 2012-06-12, Peter Laufenberg <[hidden email]> wrote:
>>>On 06/11/12 19:25, Jens A. Griepentrog wrote:
>>>> Let me know, please, whether it makes sense to modify disk geometry
>>>> for solid state disks?
>>>
>>>If you knew what physical block size your SSD worked with, you might --
>>>MIGHT -- see some benefit using that, but the 4k offsets seem to work
>>>just fine.  I doubt you would feel any difference...
>>
>> Intel's answer about X25 SSDs' erase block size on their support forums is pretty much "fuck off".
>
>Some SSD controllers use compression, so even if you have details
>of flash block sizes you can't make any calculations about partition
>alignment based on them.

The _erase_ block size surely is power of 2 and fixed. Even if the controller uses some elaborate Russian doll blocks, any formatting recommendation would be better than Intel's verbatim "we don't disclose that". It's a policy decision; they ship some bloatware Windows7-only extension.

I don't know if other manufacturers are such pricks they won't tell you how to best use their hardware, I know my next SSD won't be from Intel.

-- p

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Re: Solid state disk geometry

Kevin Chadwick-2
On Tue, 12 Jun 2012 18:31:38 +0200
Peter Laufenberg wrote:

> >Some SSD controllers use compression

I wonder if they use the average compression ratio to boost advertised
capacity?

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Re: Solid state disk geometry

Peter Laufenberg
>On Tue, 12 Jun 2012 18:31:38 +0200
>Peter Laufenberg wrote:
>
>> >Some SSD controllers use compression
>
>I wonder if they use the average compression ratio to boost advertised
>capacity?

Define "average" :)

Nah that'd be too obvious given SSDs are often used for video editing. Manufacturers are happy with the "kilo" fineprint on box stickers but who cares.

-- p

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Re: Solid state disk geometry

Jens A. Griepentrog
In reply to this post by Nick Holland
> On 06/11/12 19:25, Jens A. Griepentrog wrote:
>> Dear Mailing Listeners,
>>
>> Let me know, please, whether it makes sense to modify disk geometry
>> for solid state disks?
> no
>
>> Which meaning have the default values of cylinders,
>> heads, and sectors for these devices?
> roughly the exact same thing it has meant for IDE, SATA, and SCSI disks
> since..well...about 20 years or so...not a thing.
>
> All modern drives, and really anything made in probably the last 20
> years (i.e., anything worth putting on an OpenBSD machine) use
> translation...the "geometry" and "reality" are unrelated in any
> recognizable way.
>
>> As an example, here are my sd1 data:
>>
>> # fdisk sd1
>> Disk: sd1       geometry: 7783/255/63 [125045424 Sectors]
>> Offset: 0       Signature: 0xAA55
>>               Starting         Ending         LBA Info:
>>    #: id      C   H   S -      C   H   S [       start:        size ]
>> -------------------------------------------------------------------------------
>>    0: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
>>    1: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
>>    2: 00      0   0   0 -      0   0   0 [           0:           0 ] unused
>> *3: A6      0   1   2 -   7782 254  63 [          64:   125033831 ] OpenBSD
>>
>> Are there any disktab entries available more suitable for usual models
>> of solid state disks? At least it seemed reasonable to me to take multiples
>> of 64 blocks for the partition sizes and offsets:
> which, you will notice, is what OpenBSD does now.
>
> If you knew what physical block size your SSD worked with, you might --
> MIGHT -- see some benefit using that, but the 4k offsets seem to work
> just fine.  I doubt you would feel any difference...
>
>> # disklabel sd1
>> # /dev/rsd1c:
>> type: SCSI
>> disk: SCSI disk
>> label: SSDSA2SH064G1GC
>> duid: 78faa8282eb6f8fa
>> flags:
>> bytes/sector: 512
>> sectors/track: 63
>> tracks/cylinder: 255
>> sectors/cylinder: 16065
>> cylinders: 7783
>> total sectors: 125045424
>> boundstart: 64
>> boundend: 125033895
>> drivedata: 0
>>
>> 16 partitions:
>> #                size           offset  fstype [fsize bsize  cpg]
>>     a:          2097152               64  4.2BSD   2048 16384    1 # /
>>     b:         33554432          2097216    swap                   # none
>>     c:        125045424                0  unused
>>     d:         67108864         35651648  4.2BSD   2048 16384    1 # /home
>>
>> To make things complete, here is the dmesg output after upgrading to 5.1.
>> Many thanks to the OpenBSD developers to keep the ball in play! Radeon
>> version xf86-video-ati-6.14.3 on ATI FirePro 2270 is a big progress;
>> it gives me a brillant digital image! Sometimes there are blackscreens
>> after switching back from X11 to console, which can be resolved by rebooting
>> the machine over network. Package qcad is missing but can be compiled easily
>> from the ports collection.
>>
>> Best regards,
>> Jens
>>
> ....
>> ahc0 at pci7 dev 2 function 0 vendor "Adaptec", unknown product 0x0082
>> rev 0x02: apic 7 int 21
>> scsibus0 at ahc0: 8 targets, initiator 7
>> sd0 at scsibus0 targ 6 lun 0:<FUJITSU, MCJ3230SS, 0010>  SCSI2 0/direct
>> removable
> holy cow.  haven't seen one of those in a machine in a while. :)
> (ok, actually, I don't think I've ever seen one, period.  Or maybe I've
> got one...)
> ....
>
> Nick.
>
Dear Mailing Listeners,

Thanks to all who answered to my question to make their SSD knowledge
clear to me.

@Nick: You want to know more about my oldtimer? Oh, it's just 13 years
old, and
if it should fail once a day it will be replaced by its predecessor
MCR3230SS
which is five years younger ... Thanks to the work of Kenneth R.
Westerback these
devices work reliable even with media having sector sizes of 2048 bytes.

Greetings,
Jens