topic Re: understanding LINUX file systems in Operating System - Linux

understanding LINUX file systems

senthil_kumar_1 — Fri, 13 Mar 2009 08:38:21 GMT

Hi

I have issued "df" to view the partitions

the output of this is:

-bash-3.00$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/cciss/c0d0p1 73576124 1343912 68494692 2% /
/dev/cciss/c0d0p5 5036284 2116172 2664280 45% /admin
/dev/cciss/c0d0p13 10072456 6046692 3514096 64% /appl
/dev/cciss/c0d0p6 5036284 2541480 2238972 54% /ccm_admin
none 8206892 0 8206892 0% /dev/shm
/dev/cciss/c0d0p2 10080520 7137720 2430732 75% /home_uat
/dev/cciss/c0d0p7 5036284 1190700 3589752 25% /opt
/dev/cciss/c0d0p5 5036284 2116172 2664280 45% /projects
/dev/cciss/c0d0p9 5036284 63788 4716664 2% /tmp
/dev/cciss/c0d0p10 5036284 3239416 1541036 68% /usr
/dev/cciss/c0d0p11 5036284 937028 3843424 20% /var
/dev/sda2 24034944 7992460 14821544 36% /data6.5x
/dev/sdc1 51606124 38932668 10052020 80% /orders
/dev/mapper/vg00-lvol1
175461040 61099884 105448260 37% /data6.5
lgcms:/data_63 86016000 65756648 20101136 77% /data63
lgcms:/data_tcs 14336000 8922160 5244672 63% /datatcs
ad121991:/home 26624000 25687264 936736 97% /home

I need answer for following questions

1)what device is this "/dev/cciss/cXdXPX like /dev/cciss/c0d0p1, /dev/cciss/c0d0p5."
is it local disk or SAN disk?

2)is "/dev/sda2, /dev/sdc1" are local disks?

3) is "/dev/mapper/vg00-lvol1" is a logical volume. is the actual location is "/dev/vg00/lvol1" am i correct?

pls answer my three questions one by one.

Re: understanding LINUX file systems

Hemmetter — Fri, 13 Mar 2009 10:39:57 GMT

hi

1) local disks on smart array controller
2) maybe either, but likely SAN
3) correct

what says:
# cat /proc/scsi/scsi
?

rgds
HGH

Re: understanding LINUX file systems

senthil_kumar_1 — Fri, 13 Mar 2009 11:53:28 GMT

what is smart array contorller? pls explain.

i have worked linux with just IDE,SATA and SCSI hdds only. i am not working with "array contorllers". so pls explain me.

This system hardware is "HP ProLiant BL25p G1"

pls explain me following details.

1)what is array controller?
2)how it is connected with system.
3)what means "cciss"? is it default name?
can we change that?
4)what is "c0d0p1,c0d0p2..."?

pls explain me.

Re: understanding LINUX file systems

Ivan Ferreira — Fri, 13 Mar 2009 12:06:03 GMT

>>> what is smart array contorller

It's a disk controller that allows you to create hardware RAID disk configurations.

>>> I have worked linux with just IDE,SATA and SCSI hdds only. i am not working with "array contorllers"

Smart array controller is not a disk, is a controller, you plug to the controller SCSI or SATA disks, then you create a RAID configuration using these disks.

>>> how it is connected with system

Normally, it's an internal board.

>>> what means "cciss"? is it default name?

Yes. You cannot change that.

>>> what is "c0d0p1,c0d0p2..."?

Is the naming convention used to represent the different disks and partition. Based on other Unix variations, that would mean, controller 0 disk 0 partition 1, controller 0 disk 0 partition 2, etc.

>>> is "/dev/mapper/vg00-lvol1" is a logical volume. is the actual location is "/dev/vg00/lvol1" am i correct?

Yes.

>>> is "/dev/sda2, /dev/sdc1" are local disks?

Considering that you already have a local smart array controller, and your internal disks should be attached to it, probably, sda1 and sdc1 are not local disks.

Re: understanding LINUX file systems

smatador — Fri, 13 Mar 2009 14:53:18 GMT

Hi,

You could have more info about cciss here
http://cciss.sourceforge.net/
I think the meaning of cciss perhaps is
Compaq Command Interface for SCSI Support.

If you want more info about lvm I suggest you this links
http://tldp.org/HOWTO/LVM-HOWTO/

Re: understanding LINUX file systems

senthil_kumar_1 — Mon, 16 Mar 2009 06:12:01 GMT

Hi Hemmetter

my /proc/scsi/scsi output is

-bash-3.00$ cat scsi
Attached devices:
Host: scsi1 Channel: 00 Id: 00 Lun: 00
Vendor: HITACHI Model: OPEN-V Rev: 6004
Type: Direct-Access ANSI SCSI revision: 03
Host: scsi1 Channel: 00 Id: 00 Lun: 01
Vendor: HITACHI Model: OPEN-V Rev: 6004
Type: Direct-Access ANSI SCSI revision: 03
Host: scsi1 Channel: 00 Id: 00 Lun: 02
Vendor: HITACHI Model: OPEN-V Rev: 6004
Type: Direct-Access ANSI SCSI revision: 03
Host: scsi1 Channel: 00 Id: 00 Lun: 03
Vendor: HITACHI Model: OPEN-V*2 Rev: 6004
Type: Direct-Access ANSI SCSI revision: 03

pls explain me the details of above things.

you said that "/dev/cciss/c0d0p1,c0d0p2" is smart arry contorller.

I am understanding some thing about smart contorller pls check me.

1) The scsi card is connected with I/O slots.
2) In that scsi card the Controllers are available like c0, c1, c2 ...
3) we are connecting a scsi cable to that controller.
4) In one scsi cable we can connect 14 scsi hdds.
5) In scsi hdd we have to select device position jumper setting like d0, d1, d2 ...
6) For example. we have connected one scsi hdd (setting jumper as d0) with Controller C0. then it's device files looks like "c0d0".
7) If that device "c0d0" have three partitions than the device files partitions looks like "c0d0p1, c0d0p2, c0d0p3.
8) cciss is firmware available with in the ROM chip scsi card. which is used to control the scsi card and scsi hdds.
9) Are all above my understanding are correct?

then, I have following questions, pls answer me.

1) how many pins one scsi controller has?
2) how many controllers can be in one scsi card (scsi adaptor).
3) how many scsi hdds we can connect in a single scsi controller.
4) how to view how many scsi hdds are connected in a single controller.
5) how to view how many total scsi hdds are available in whole system.
6) how to view how many scsi cards (scsi adaptors) are connected with in a single system.
7) how to create the partitions? is it using fdisk like "fdisk /dev/cciss/c0d0"
8) is partition creation is normal like IDE hdd and SATA hdd.
9)how to view whether RAID is configured?
10) what RAID configured?

pls answer my questions one by one.

Re: understanding LINUX file systems

Nuwan Alwis — Tue, 17 Mar 2009 03:08:09 GMT

Hi Kumar,
Wel it seems to me that you have taken this HW RAID concept as so complicated.

Forget all u know about HW RAID controllers for a moment before reading the next section.

1.HW RAID Controller is a device attached to your system board.
2.All your Hard disks get attached to this controller when you plug in a HDD to the server.
3.You can define RAID level 0,1,5 on your physical hard disks through the RAID controller by accessing its GUI by booting your server with HP smart start CD or menu driven interface is also available by pressing F8 when server detect RAID Controller at the boot time.

4.All the settings you made to disks through RAID controller is not visible to the OS.
Example:
you have 2 x 146GB SAS disks plugged in to your server.

You create RAID1 mirror on them through HW RAID controller.

Now your system see 1 x ~146GB disk.

Also you can create Logical disks on this 146GB disk.
Say you crate 100GB logical disk and 46GB logical disk.

and save settings on the HW RAID controller.

Now when you install windows on the server, it see server has 2 Hard drives
1 x 100GB
1 x 46GB

and you can partition them using windows as u like.

this is all controlled by HW RAID.

Now say 1 of your physical 146 HDD failed.
Now your Mirror is gone...! but

server still see 2 disk drives
1 x 100GB
1 x 46GB
and all your partitions created using windows.

When you replace the Failed hard disk the controller will copy all the disk data to the new disk.

No over head on the OS on this copy process.

Hope this will clear out your confusion.

About the questions.
1)dont know what u mean by pins. but connectors per card is depends normally 8
2)normally 1 card have 1 controller
3)depends on the model DL380G5 with E200i can connect 8 disks.
4)HP smart start/or the online management info tools can provide the details.
5)same as 4
6)same as 4
7)yes you can use the traditional method of fdisk or parted.
8)yes
9)same as 4
10)same as 4

Good Luck...!

Re: understanding LINUX file systems

senthil_kumar_1 — Tue, 17 Mar 2009 06:18:52 GMT

Hi Nuwan Alwis

I am able to access that system from being in remote.

So I am not able to view the system physically. but I can login in to the LINUX.

so is there any possibility to view following details by just log in to linux only.

IF RAID is configured:

1) how to view whether RAID is configured or not?

2) what RAID configured?

3) do you think that RAID is configured in my linux when you see "df" command output.

4) how to view how many scsi hdds are connected in a single controller.

5) how to view that how many total scsi hdds are available in whole system.

6) how to view that How many logical partition availabe in RAID?

7) what are the device files will be created for the disks connected with RAID like c0d0,c0d1..

8) If RAID is configure c0d0, c0d1 ... all are logical partitions 1,2 .. created in RAID?

9) How to know if any one hdd fails in RAID.

10) How to replace that HDD. do we need to switchoff and replace ?

IF RAID is not configured:

1) Is it must that we have to configure any of RAIDs if we are using RAID controller.

2) If we have connected 2 scsi hdds with RAID controller but RAID is not configured. then the two hdds device files will look like "c0d0", "c0d1" .... am i correct?

3) If we have one RAID controller and we have connected two scsi hdds and RAID is not configured. then the device files will look like "/dev/cciss/c0d0, /dev/cciss/c0d1" am i correct?

4) If we have two RAID controllers connected with a system. and we have connected two scsi hdd with each RAID controllers. then how the device files will be.

pls answer for all my questions above one by one.

Re: understanding LINUX file systems

Nuwan Alwis — Wed, 18 Mar 2009 03:23:15 GMT

Hi Kumar,
For your Question number 1,2 the answer would be Access HP SMH(System management Homepage) Via browser.

http://h18013.www1.hp.com/products/quickspecs/11654_na/11654_na.html

this tools gives you the hardware info of the server in your browser.

http://docs.hp.com/en/381372-004/ch08.html?btnNext=next%A0%BB

Q3 > Wel looking at your df im unable to tel the RAID info Because as i told you its not possible to access HW RAID info from OS.

but this server have a configured LVM.

maybe fdisk -l is more sutable when talking info about disks visible to system.

Q4, Q5> as Q1,Q2

Q6> fdisk -l

Q7> As My friend Ivan Ferreira told you early
Device files crated attache to a scssi will be like
[c0(controller ID)d0(disk ID)p0(partition)]

Q8> No these are partitions crated at install time.

Q9> Not too sure about this.

Q10> No need of doing so if your server is new and supports hot swapping.

FYI
you can assign a spare disks when you configure HW RAID controller so it will automatically get replaced. but anyway you have to Physically remove the failed one

No need of bring the server offline

your Section 2

Q1> by default new proliant servers get automatically configured RAID at initial start up. say if you had 3 disks on the server when you start up the server for the first time controller will crate a RAID 5.

Q2>Yes

Q3>seems to me its Q2 again

Q4>it would be c0 , c1

Good Luck..!