[linux-lvm] Max storage size per system

[linux-lvm] Max storage size per system

[Stephan Austermuehle]

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Hello,

what is the absolut maximum storage capacity that can be managed on a
single Linux 2.4 system with LVM?

Kind regards,

Stephan

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Re: [linux-lvm] Max storage size per system

[Jon Bendtsen]

Stephan Austermuehle wrote:
> 
> Hello,
> 
> what is the absolut maximum storage capacity that can be managed on a
> single Linux 2.4 system with LVM?

man vgcreate
       -s, --physicalextentsize PhysicalExtentSize[kKmMgGtT]
              Sets  the physical extent size on physical volumes of this
volume group.
              A size suffix (k for kilobytes up  to  t  for  terabytes) 
is  optional,
              megabytes  is the default if no suffix is present.  Values
can be from 8
              KB to 16 GB in powers of 2. The default of 4 MB causes
maximum LV  sizes
              of  ~256GB because as many as ~64k extents are supported
per LV. In case
              larger maximum LV sizes are needed (later), you need to
set the PE  size
              to  a  larger value as well. Later changes of the PE size
in an existing
              VG are not supported.

So, this means you can allocate 
64k * 16G == 64*1024 * 16*1024*1024*1024 == 1125899906842624 bytes ==
1024Tera Bytes,

Hovever, 
       To limit kernel memory usage, there is a limit of 65536 physical 
extents  (PE)
       per  logical volume, so the PE size determines the maximum
logical volume size.
       The default PE size of 4MB limits a single logical volume to
256GB (see the  -s
       option  to raise that limit).  There is also (as of Linux 2.4) a
kernel limita­
       tion of 2TB per block device.

So, this would mean 2TB pr. LV, but there can also be a number of LV's.
I dont remember how many, but proberly a power of 2, like 256 or 64k. 
But wait, there is more...
You can have more than one VG system on your linux (no idea how many, i
have had 2)
So, all in all, i would asume you can have MANY TERABYTES. Possibly
Penta? bytes ?

How much space do you need anyway ?




JonB

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Tue, Mar 04, 2003 at 03:30:29PM +0100, Jon Bendtsen wrote:

> So, this would mean 2TB pr. LV, but there can also be a number of LV's.

Okay, so the LVM can manage really large disk storage. Does anybody know
whether the number of mounted filesystem per Linux system is limited?

> How much space do you need anyway ?

100+ Terabytes

Kind regards,

Stephan

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Re: [linux-lvm] Max storage size per system

[Anders Widman]

> On Tue, Mar 04, 2003 at 03:30:29PM +0100, Jon Bendtsen wrote:

>> So, this would mean 2TB pr. LV, but there can also be a number of LV's.

> Okay, so the LVM can manage really large disk storage. Does anybody know
> whether the number of mounted filesystem per Linux system is limited?

>> How much space do you need anyway ?

> 100+ Terabytes

Hm,  sounds  like  lots.  :)  What kind of devices will you be running
with.  Even  with  300GB  drives  you will need 300-400 of them to get
100TB.




> Kind regards,

> Stephan


   



--------
PGP public key: https://tnonline.net/secure/pgp_key.txt

Re: [linux-lvm] Max storage size per system

[Jesse Keating]

On Wednesday 05 March 2003 07:05, Anders Widman wrote:
> Hm,  sounds  like  lots.  :)  What kind of devices will you be running
> with.  Even  with  300GB  drives  you will need 300-400 of them to get
> 100TB.

Easily achieved w/ such technologies as iscsi and hyperscsi (;

-- 
Jesse Keating RHCE MCSE
Pogo Linux -- Support Tech
tel: (888) 828-7646 ex: 436

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Wed, Mar 05, 2003 at 08:54:10AM -0800, Jesse Keating wrote:

> Easily achieved w/ such technologies as iscsi and hyperscsi (;

Which are nothing but trash.

Kind regards,

Stephan

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Re: [linux-lvm] Max storage size per system

[Petro]

On Wed, Mar 05, 2003 at 11:50:52AM -0800, Stephan Austermuehle wrote:
> On Wed, Mar 05, 2003 at 08:54:10AM -0800, Jesse Keating wrote:
> > Easily achieved w/ such technologies as iscsi and hyperscsi (;
> Which are nothing but trash.

    Hey man, don't pull any punches, tell us how you *Really* feel. 

-- 
"On two occasions, I have been asked [by members of Parliament], 'Pray, 
Mr. Babbage, if you put into the machine wrong figures, will the right 
answers come out?' I am not able to rightly apprehend the kind of confusion 
of ideas that could provoke such a question." -- Charles Babbage 

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Thu, Mar 06, 2003 at 05:34:31PM -0800, Petro wrote:

> Hey man, don't pull any punches, tell us how you *Really* feel. 

Well, iSCSI was developed and pushed by some networking guys with
Ethernet in mind to get into the storage market without developing know
how for a really efficient data link. So iSCSI has to handle lots of
overhead: SCSI commands are encapsulated in IP, IP is encapuslated in
Ethernet. This leads to bad performance (latency, throughput) compared
to a Fibre Channel connection with the same link speed. Maybe the
performance impact will become negligible with 10G or 100G Ethernet but
at the moment we don't have these technologies available.

Stephan

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Re: [linux-lvm] Max storage size per system

[Jesse Keating]

On Friday 07 March 2003 06:20, Stephan Austermuehle uttered:
> Well, iSCSI was developed and pushed by some networking guys with
> Ethernet in mind to get into the storage market without developing know
> how for a really efficient data link. So iSCSI has to handle lots of
> overhead: SCSI commands are encapsulated in IP, IP is encapuslated in
> Ethernet. This leads to bad performance (latency, throughput) compared
> to a Fibre Channel connection with the same link speed. Maybe the
> performance impact will become negligible with 10G or 100G Ethernet but
> at the moment we don't have these technologies available.

This speaks nothing of HyperSCSI which is indepenant of TCP/IP and all of it's 
ugly overhead.  Hyperscsi runs in raw ethernet, no TCP/IP even need be on the 
wire.  Data writing w/ HyperSCSI is far faster than with NFS or iSCSI.

-- 
Jesse Keating RHCE MCSE
Pogo Linux -- Support Tech
tel: 888.828.7646

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Wed, Mar 05, 2003 at 04:05:32PM +0100, Anders Widman wrote:

> Hm,  sounds  like  lots.  :)  What kind of devices will you be running
> with.  Even  with  300GB  drives  you will need 300-400 of them to get
> 100TB.

A single HP XP 1024 (which is an OEM product of a HDS Lightning) stores
130 TB with a 7p1 RAID5 configuration and 146 GB disks.

Kind regards,

Stephan

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Re: [linux-lvm] Max storage size per system

[jon+lvm]

On Wed, Mar 05, 2003 at 08:45:51PM +0100, Stephan Austermuehle wrote:
> On Wed, Mar 05, 2003 at 04:05:32PM +0100, Anders Widman wrote:
> 
> > Hm,  sounds  like  lots.  :)  What kind of devices will you be running
> > with.  Even  with  300GB  drives  you will need 300-400 of them to get
> > 100TB.
> 
> A single HP XP 1024 (which is an OEM product of a HDS Lightning) stores
> 130 TB with a 7p1 RAID5 configuration and 146 GB disks.

hmm, that would need 130T/0.146T = 890 disks. And running raid 5...
personaly i dont like raid5, because if you loose more than one
disk your data are gone, and with this ammount of disks, i expect
failure rather often. (it's proberly not one big raid5 array,
but that just makes it need more disks).



JonB

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Thu, Mar 06, 2003 at 05:21:50PM +0100, jon+lvm@silicide.dk wrote:

> hmm, that would need 130T/0.146T = 890 disks. And running raid 5...

Please have a look at the following links. A single HDS Lightning
(aka HP XP 1024) can address up to 1,024 disks.

	http://www.hp.com/products1/storage/products/disk_arrays/highend/xp1024/index.html

	http://www.hds.com/products/systems/9900v/

> personaly i dont like raid5, because if you loose more than one disk
> your data are gone, and with this ammount of disks, i expect failure
> rather often. (it's proberly not one big raid5 array, but that just
> makes it need more disks).

I prefer RAID 1 (or RAID 10), too, but sometimes one has to use RAID 5.
A common strategy is to put a higher number of hot spare drives in one
system. Another (somewhat newer) strategy is to use two rotating parity
drives per RAID set.

Stephan

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Re: [linux-lvm] Max storage size per system

[Jon Bendtsen]

Stephan Austermuehle wrote:
> 
> On Thu, Mar 06, 2003 at 05:21:50PM +0100, jon+lvm@silicide.dk wrote:
> 
> > hmm, that would need 130T/0.146T = 890 disks. And running raid 5...
> 
> Please have a look at the following links. A single HDS Lightning
> (aka HP XP 1024) can address up to 1,024 disks.
> 
>         http://www.hp.com/products1/storage/products/disk_arrays/highend/xp1024/index.html
> 
>         http://www.hds.com/products/systems/9900v/

nice, imagien all that porn ;-D

 
> > personaly i dont like raid5, because if you loose more than one disk
> > your data are gone, and with this ammount of disks, i expect failure
> > rather often. (it's proberly not one big raid5 array, but that just
> > makes it need more disks).
> 
> I prefer RAID 1 (or RAID 10), too, but sometimes one has to use RAID 5.
> A common strategy is to put a higher number of hot spare drives in one
> system. Another (somewhat newer) strategy is to use two rotating parity
> drives per RAID set.

2 rotating parity disks ? Can you elaborate on how that works ?
I have thought about using something else than raid5, where you would
split the data across a number of disks, AND use a mirrored device for
storing the parity on.



JonB

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Fri, Mar 07, 2003 at 04:36:14PM +0100, Jon Bendtsen wrote:

> 2 rotating parity disks ? Can you elaborate on how that works ?

"The Mathematics behind the RAID 5DP":

	http://www.hp.com/products1/storage/products/disk_arrays/infolibrary/mathematics_behind_RAID_5DP.pdf

"Analysis of RAID 5DP":

	http://www.hp.com/products1/storage/products/disk_arrays/infolibrary/analysis_0f_RAID_5DP.pdf

Kind regards,

Stephan

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Re: [linux-lvm] Max storage size per system

[Jon Bendtsen]

Stephan Austermuehle wrote:
> 
> On Fri, Mar 07, 2003 at 04:36:14PM +0100, Jon Bendtsen wrote:
> 
> > 2 rotating parity disks ? Can you elaborate on how that works ?
> 
> "The Mathematics behind the RAID 5DP":
> 
>         http://www.hp.com/products1/storage/products/disk_arrays/infolibrary/mathematics_behind_RAID_5DP.pdf
> 
> "Analysis of RAID 5DP":
> 
>         http://www.hp.com/products1/storage/products/disk_arrays/infolibrary/analysis_0f_RAID_5DP.pdf


thanks.



JonB

Re: [linux-lvm] Max storage size per system

[Wiktor Wodecki]

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Hello,

On Tue, Mar 04, 2003 at 03:41:21PM +0100, Stephan Austermuehle wrote:
> Okay, so the LVM can manage really large disk storage. Does anybody know
> whether the number of mounted filesystem per Linux system is limited?

yes, it is limited through the kernel. There are two ways out of it:

a) increase the number (fiddle through the source, recompile, reboot)
b) use the automounter

If you don't need all filesystems mounted at once I'd suggest the second
approach. (e.g. for samba or backup store, whatever)

-- 
Regards,

Wiktor Wodecki

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[linux-lvm] can i extend a volumen bigger 256 gigas ?thx

[fnt]

Hello,

It is possible to extend a volumen more than 256 gigas?
it doesnt let me grow the space.
this is muy info :
root]# cat /proc/lvm/global
LVM module LVM version 1.0.3(19/02/2002)

Total:  1 VG  2 PVs  1 LV (1 LV open 1 times)

Global: 449424 bytes malloced   IOP version: 10   1175 days 12:40:03 active

VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
  Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used  180932608
/44173 free
  PVs: [AA] ide/host0/bus0/target0/lun0/part4 113950720 /27820   113950720
/27820          0 /0
       [AA] ide/host0/bus0/target1/lun0/part1 180932608 /44173          0 /0
180932608 /44173
    LV:  [AWDL  ] vol1                     113950720 /27820    1x open

i have installed: lvm-1.0.1-2mdk.i586.rpm

thanks on advanced.

Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx

[Erik Nugent]

when you create your volume group you can change the extent size with
the -s switch. recent versions of LVM use 32MB as the default which
gives you a max LV of about 2TB. the old default extent size of 4MB gave
you about 255GB max LV size.

On Mon, 2003-05-05 at 13:39, fnt wrote:
> Hello,
> 
> It is possible to extend a volumen more than 256 gigas?
> it doesnt let me grow the space.
> this is muy info :
> root]# cat /proc/lvm/global
> LVM module LVM version 1.0.3(19/02/2002)
> 
> Total:  1 VG  2 PVs  1 LV (1 LV open 1 times)
> 
> Global: 449424 bytes malloced   IOP version: 10   1175 days 12:40:03 active
> 
> VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
>   Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used  180932608
> /44173 free
>   PVs: [AA] ide/host0/bus0/target0/lun0/part4 113950720 /27820   113950720
> /27820          0 /0
>        [AA] ide/host0/bus0/target1/lun0/part1 180932608 /44173          0 /0
> 180932608 /44173
>     LV:  [AWDL  ] vol1                     113950720 /27820    1x open
> 
> i have installed: lvm-1.0.1-2mdk.i586.rpm
> 
> thanks on advanced.
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
-- 
====================================
Erik Nugent
System Administrator
Department of Computer Science
The University of Montana, Missoula
(406) 243-2812
====================================
"Tee off and fly freely"
	"Steady" Ed
====================================

Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx

[Daniel Barbar]

Yes, it is possible. What's the command you're using and the error 
you get? The maximum size of a logical volume is a function of the 
volume group physical extent size (I don't remember the details). 
You may need to create the volume group with a larger physical 
extent in order to have larger capacity logical volumes, for 
instance, 'vgcreate -s 16m ...'. As far as I know, you do have to 
recreate the volume group in order to change the physical extent 
size. Hope this helps.

---
Daniel Barbar

fnt wrote:
> Hello,
> 
> It is possible to extend a volumen more than 256 gigas?
> it doesnt let me grow the space.
> this is muy info :
> root]# cat /proc/lvm/global
> LVM module LVM version 1.0.3(19/02/2002)
> 
> Total:  1 VG  2 PVs  1 LV (1 LV open 1 times)
> 
> Global: 449424 bytes malloced   IOP version: 10   1175 days 12:40:03 active
> 
> VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
>   Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used  180932608
> /44173 free
>   PVs: [AA] ide/host0/bus0/target0/lun0/part4 113950720 /27820   113950720
> /27820          0 /0
>        [AA] ide/host0/bus0/target1/lun0/part1 180932608 /44173          0 /0
> 180932608 /44173
>     LV:  [AWDL  ] vol1                     113950720 /27820    1x open
> 
> i have installed: lvm-1.0.1-2mdk.i586.rpm
> 
> thanks on advanced.
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

-- 
Daniel Barbar

Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx-thanks for ur time

[fnt]

thx for ur time.
----- Original Message -----
From: "Daniel Barbar" <dbarbar@legato.com>
To: <linux-lvm@sistina.com>
Sent: Monday, May 05, 2003 10:40 PM
Subject: Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx


> Yes, it is possible. What's the command you're using and the error
> you get? The maximum size of a logical volume is a function of the
> volume group physical extent size (I don't remember the details).
> You may need to create the volume group with a larger physical
> extent in order to have larger capacity logical volumes, for
> instance, 'vgcreate -s 16m ...'. As far as I know, you do have to
> recreate the volume group in order to change the physical extent
> size. Hope this helps.
>
> ---
> Daniel Barbar
>
> fnt wrote:
> > Hello,
> >
> > It is possible to extend a volumen more than 256 gigas?
> > it doesnt let me grow the space.
> > this is muy info :
> > root]# cat /proc/lvm/global
> > LVM module LVM version 1.0.3(19/02/2002)
> >
> > Total:  1 VG  2 PVs  1 LV (1 LV open 1 times)
> >
> > Global: 449424 bytes malloced   IOP version: 10   1175 days 12:40:03
active
> >
> > VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
> >   Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used
180932608
> > /44173 free
> >   PVs: [AA] ide/host0/bus0/target0/lun0/part4 113950720 /27820
113950720
> > /27820          0 /0
> >        [AA] ide/host0/bus0/target1/lun0/part1 180932608 /44173
0 /0
> > 180932608 /44173
> >     LV:  [AWDL  ] vol1                     113950720 /27820    1x open
> >
> > i have installed: lvm-1.0.1-2mdk.i586.rpm
> >
> > thanks on advanced.
> >
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
> --
> Daniel Barbar
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx

[fnt]

Hi,

Recreating the VG , i will keep the data?
thx

Joaquin Ign.
Best Regads-
---- Original Message -----
From: "Daniel Barbar" <dbarbar@legato.com>
To: <linux-lvm@sistina.com>
Sent: Monday, May 05, 2003 10:40 PM
Subject: Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx


> Yes, it is possible. What's the command you're using and the error
> you get? The maximum size of a logical volume is a function of the
> volume group physical extent size (I don't remember the details).
> You may need to create the volume group with a larger physical
> extent in order to have larger capacity logical volumes, for
> instance, 'vgcreate -s 16m ...'. As far as I know, you do have to
> recreate the volume group in order to change the physical extent
> size. Hope this helps.
>
> ---
> Daniel Barbar
>
> fnt wrote:
> > Hello,
> >
> > It is possible to extend a volumen more than 256 gigas?
> > it doesnt let me grow the space.
> > this is muy info :
> > root]# cat /proc/lvm/global
> > LVM module LVM version 1.0.3(19/02/2002)
> >
> > Total:  1 VG  2 PVs  1 LV (1 LV open 1 times)
> >
> > Global: 449424 bytes malloced   IOP version: 10   1175 days 12:40:03
active
> >
> > VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
> >   Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used
180932608
> > /44173 free
> >   PVs: [AA] ide/host0/bus0/target0/lun0/part4 113950720 /27820
113950720
> > /27820          0 /0
> >        [AA] ide/host0/bus0/target1/lun0/part1 180932608 /44173
0 /0
> > 180932608 /44173
> >     LV:  [AWDL  ] vol1                     113950720 /27820    1x open
> >
> > i have installed: lvm-1.0.1-2mdk.i586.rpm
> >
> > thanks on advanced.
> >
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
> --
> Daniel Barbar
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] can i extend a volumen bigger 256 gigas ?thx

[Jose Luis Domingo Lopez]

On Monday, 05 May 2003, at 21:39:04 +0200,
fnt wrote:

> It is possible to extend a volumen more than 256 gigas?
>
Yes.

> it doesnt let me grow the space.
> this is muy info :
> root]# cat /proc/lvm/global
> VG:  gl  [2 PV, 1 LV/1 open]  PE Size: 4096 KB
>   Usage [KB/PE]: 294883328 /71993 total  113950720 /27820 used  180932608
>
Directly from vgcreate(8) (lvm2 tools, version 1.95.15-1 (Debian Sid)):

   To limit kernel memory usage,  there  is  a  limit  of  65536 physical
   extents  (PE) per logical volume, so the PE size determines the maximum
   logical volume size.  The default PE size of 4MB limits a single logi-
   cal  volume to 256GB (see the -s option to raise that limit). There is
   also (as of Linux 2.4) a kernel limitation of 2TB per block device.

As far as I remember, this limit is also there in LVM1.

Hope it helps.

-- 
Jose Luis Domingo Lopez
Linux Registered User #189436     Debian Linux Sid (Linux 2.5.68)

Re: [linux-lvm] Max storage size per system

[jon+lvm]

On Tue, Mar 04, 2003 at 03:41:21PM +0100, Stephan Austermuehle wrote:
> On Tue, Mar 04, 2003 at 03:30:29PM +0100, Jon Bendtsen wrote:
> 
> > So, this would mean 2TB pr. LV, but there can also be a number of LV's.
> 
> Okay, so the LVM can manage really large disk storage. Does anybody know
> whether the number of mounted filesystem per Linux system is limited?

i think you need to read up on how LVM works. In the bottom you have pv's.
physical volumes. They are divided into physical extends which can be from
4k to 16G. But you set this for the hole VolumenGroup. The VG has a name,
and can span several physical devices. Inside this VG, you make a LV,
LogicalVolumen. The LV can hold 64k PE, physical extends, which if you
make them 16G... means 1024T ? however, the LV is a blockdevice, and
thus an LV cant be bigger than 2T. So you would have to use many LV's
to store 100+T.


> > How much space do you need anyway ?
> 
> 100+ Terabytes

What do you need it for ?




JonB

Re: [linux-lvm] Max storage size per system

[Heinz J . Mauelshagen]

Maximum of 256 LVs * 2TB in stock 2.4 = 512TB.

On Tue, Mar 04, 2003 at 12:48:52PM +0100, Stephan Austermuehle wrote:
> Hello,
> 
> what is the absolut maximum storage capacity that can be managed on a
> single Linux 2.4 system with LVM?
> 
> Kind regards,
> 
> Stephan



-- 

Regards,
Heinz    -- The LVM Guy --

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    Nevertheless it needs not so stupid people to solve them ***

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RE: [linux-lvm] Max storage size per system

[Sharad Tiwari]

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Hi, 

	Please ignore the disclaimer that comes attached with this mail
... I am trying to get it removed ... just don't have much control on
it!!! 
I am not a part of the lvm-devel mailing list so please just put me in
the CC ...

I am sory for these dumb questions ... but I am a beginner in this world
an hence I need to put forth these rather stupid questions ...
Here are my questions ???

1) Why does lvm need to register itself both as a block device and a
character device ??? (This is what I could make out on seeing the code ,
please correct me if I am wrong)

2) I need to provide an interface in the user-space for doing the
following operations : 

a) open volume device
b) read volume device
c) write volume device
d) ioctl operations on volume device
e) close volume device ...

these perhaps correspond to the following functions in the kernel ...

static int lvm_blk_ioctl(struct inode *, struct file *, uint, ulong);
static int lvm_blk_open(struct inode *, struct file *);

static int lvm_blk_close(struct inode *, struct file *);
static int lvm_get_snapshot_use_rate(lv_t * lv_ptr, void *arg);
static int lvm_user_bmap(struct inode *, struct lv_bmap *);

static int lvm_chr_open(struct inode *, struct file *);
static int lvm_chr_close(struct inode *, struct file *);
static int lvm_chr_ioctl(struct inode *, struct file *, uint, ulong);

Could some-one help me in this ... the library liblvm can be used
perhaps ...I could not make out how the functions in 
liblvm-10.a (available with the lvm-1.0.6.tar.gz)does this ...

Could some-one help me out here ...


Thanks for the help ...
Sharad.



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re[2]: [linux-lvm] Max storage size per system

[Greg Freemyer]

 >>  On Wednesday 05 March 2003 07:05, Anders Widman wrote:
 >>  > Hm,  sounds  like  lots.  :)  What kind of devices will you be running
 >>  > with.  Even  with  300GB  drives  you will need 300-400 of them to get
 >>  > 100TB.

 >>  Easily achieved w/ such technologies as iscsi and hyperscsi (;

Don't leave out good old FC (Fibre Channel).

I just went to a seminar where EMC is going to start supporting 300 GB ide drives in their CX line.  (To be announced shortly.)

I think a maxed out cx600 holds 240 drives.  (Some of these may still need to be fibre drives, not ide.)

So you put in a couple of CX600s full of drives and use LVM to manage it.

The only trouble is $$, not technology.

Greg
-- 
Greg Freemyer

Re: [linux-lvm] Max storage size per system

[Stephan Austermuehle]

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On Wed, Mar 05, 2003 at 12:42:40PM -0500, Greg Freemyer wrote:

> The only trouble is $$, not technology.

If you need to store that much of data the deployment costs are not
necessarily the problem. Such a system will be managed and needs some
support and service (TCO).

Kind regards,

Stephan

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