iscsi interview questions
Top iscsi frequently asked interview questions
I am using open-iscsi initiator and using bnx2i (broadcom offload driver)
However, there are many related drivers - bnx2, bnx2x and cnic drivers available.
Suppose that I want to perform discovery/login from the initiator using offload driver; In this case I prepare the iface configuration file for bnx2i and specify it while performing discovery. In this case bnx2i module is used instead of tcp.
Now I am getting confused about the role of other drivers - bnx2, bnx2x and cnic drivers. Are these drivers necessary for supporting bnx2i? Can someone elaborate on the data flow and dependency when using initiator and bnx2i?
Source: (StackOverflow)
Is it possible for multiple computers to connect to the same target at the same time, using the same initiator IQN?
Thank you.
Source: (StackOverflow)
I am trying to craft a regexp to validate iSCSI qualified names. An example of a qualified name is iqn.2011-08.com.example:storage This is example is minimal, I have seen other examples that are more extended.
So far what I have to validate off of it this:
print "Enter a new target name: ";
my $target_name = <STDIN>;
chomp $target_name;
if ($target_name =~ /^iqn\.\d{4}-\d{2}/xmi) {
print GREEN . "Target name is valid!" . RESET . "\n";
} else {
print RED . "Target name is not valid!" . RESET . "\n";
}
How can I extend that to work with rest up to the : I am not going to parse after the : becuase it is a description tag.
Is there a limit to how big a domain name can be?
Source: (StackOverflow)
I'm trying to discover an iscsi target and am getting the following error:
iscsiadm: Connection to Discovery Address 172.18.1.4 closed
iscsiadm: Login I/O error, failed to receive a PDU
My target config is the following:
<target iqn.2012-4.com.mylab:first >
backing-store /dev/vgsrv/storage
initiator-address 172.18.1.1
</target>
Here are my details:
my initiator IP : 172.18.1.4
my target IP : 172.18.1.1
kernel : Linux 2.6.32-504.el6.x86_64
iscsid version 6.2.0-873.13.el6
Any tips why I'm facing this issue? All firewalls and ips are off.
Source: (StackOverflow)
On a local machine, I can just do
cat /etc/iscsi/initiatorname.iscsi
to get the IQN that is sent to targets when establishing an ISCSI session.
What I am trying to find out is whether it is possible to establish another machine's initiator IQN without ssh'ing to it.
This is because, given a set of IPs or hostnames of machines I have no control over, I need to set up targets to allow ISCSI logins from those machines only.
It doesn't seem to be possible using, e.g., iscsiadm. I'm assuming the answer is No, but I'm no expert in ISCSI, so asking anyway.
If the answer is No, we'll have to deal with the problem in some other way, perhaps by requiring the initiators to be set up with IQNs from a known pool, or even that the IQN is set to the same on all those machines (I suspect there might be adverse consequences with the latter workaround, but I'm not sure).
Source: (StackOverflow)
I am new to iSCSI programming. I have security camera videos written in iSCSI blocks in a SAN. I need to construct playback of the some video from those blocks. I have hard time finding any tutorial or lead to solve this issue.
Thanks in advance.
Source: (StackOverflow)
I'm studying the iSCSI protocol and now im in the phase where i used Wireshark to capture the packets to see, which packets are used to mantain the sessions active, and when i copy a file to my logical volume, which packets are traded. Below is an image of that. I would appreciate help on 
trying to understand or pointing me to any website that explains it.
Source: (StackOverflow)
We use an ubuntu 12.04 LTS Server as ISCSI Target, this server used three network interface cards, each is configured for a different workloads and is configured in different network.
One nic is for internal traffic, the second is for drbd replication and the third on is for extern (public).
Unfortunatly the clients which consume the iscsi target server, wasnt correct configured and connect to the iscsi target server via the public interface.
If we now change in the connect-statement the portal for the internal iface with the same iqn, we see old contents inside the mountpoint. We only usw an img-file on the target-server as the lun.
if i discover from a client i get the result:
1.1.1.1:3260,1 iqn.2020-12.de.domain.iscsi:www
172.16.0.13:3260,1 iqn.2020-12.de.domain.iscsi:www
192.168.0.13:3260,1 iqn.2020-12.de.domain.iscsi:www
(IP Adresses changed for post)
the current login-statement is:
iscsiadm -m node --targetname "iqn.2020-12.de.domain.iscsi:www" --portal "1.1.1.1:3260" --login
with this, all is working fine and all folders we except to be there are inplace.
If we now try to connect via the internal portal with:
iscsiadm -m node --targetname "iqn.2020-12.de.domain.iscsi:www" --portal "172.16.0.13:3260" --login
some folders are missing.
We use OCFS2 for concurrent access, this as a side note
thanks for your time
Source: (StackOverflow)
I am facing data corruption issue when using libaio to read data from an iscsi disk.
Steps Performed:
- Allocate buffer(1MB) using posix_memalign with 4K Allignemnt.
- Fill the buffer with 9 before submitting io.
- Open iscsi disk with O_DIRECT flag.
- Submit read requests using io_submit of libaio
- In parallel execute vfork()
- Call io_getevents and wait for io to complete
- Check crc of buffer retrieved in io_getevents to check data is consistent or not.
The CRC matching is failed for some offset.
The CRC check is failing for some io. Before submitting io request i am filling the buffer with a pattern say '9', and i have analyzed the corrupted buffer and observed thatsome part of data in the buffer remains unchange, i.e same 9 is there in some part of buffer.
The buffer is allocated with , 4K alligned using posix_memalign().
Is some one has also faced similar issue ? If there is any known limitation will you please share with me.
Source: (StackOverflow)
I want to extract the attached iSCSI device of a remote machine
dev_by_path="/dev/disk/by-path/ip-10.1.1.240:3260-iscsi-iqn.2013-12.com.ryussi:swift1-lun-0"
DEVICE=`ssh -i key.pem root@10.0.0.2 'bash -s' << 'ENDSSH'
basename $(readlink $dev_by_path)
ENDSSH`
It gives error:
readlink: missing operand
Try `readlink --help' for more information.
basename: missing operand
Try `basename --help' for more information
However if I do
DEVICE=`ssh -i key.pem root@10.0.0.2 'bash -s' << 'ENDSSH'
basename $(readlink "/dev/disk/by-path/ip-10.1.1.240:3260-iscsi-iqn.2013-12.com.ryussi:swift1-lun-0")
ENDSSH`
then it executes successfully and echo $DEVICE gives sda.
How should I execute this.
Source: (StackOverflow)
I have created iscsi targets in ubuntu 14.04 using targetcli, is there any way to know the details of who has connected to the targets(like ip, connectection status)
Source: (StackOverflow)
In PowerShell I'm trying to get the drive letter that an ISCSI target is mapped to. I'm using the following to get the ISCSI initiator name.
Get-IscsiTarget | ? {$_.IsConnected -eq $True} | Select -ExpandProperty NodeAddress
I have tried using Get-Disk | Select * and Get-PSDrive | Select * but these cmdlets do not seem to have any fields that I can link a target to, to obtain its drive letter.
Source: (StackOverflow)
I have this small PS script which outputs a list of ip adresses and their respective ID's for the iSCSI initiator. Now I want to do some more extensive stuff with this information and since I don't really know PS and the way it works I would like to migrate the script to python and continue from there.
Now the PS script obtains these via the WMI. Here it is:
function Get-IscsiPortNumber {
$PortalSummary = @()
$portalInfo = get-wmiobject -namespace root\wmi -class msiscsi_portalinfoclass
$eScriptBlock ={([Net.IPAddress]$_.ipaddr.IPV4Address).IPAddressToString}
$customLabel = @{Label="IpAddress"; expression = $eScriptBlock}
foreach ($portal in $portalInfo) {
foreach ($p in ($portal.portalinformation)) {
$CurrentPort = New-Object PsObject -Property @{ `
NetID = $p.port;`
IP = ([net.ipaddress]$p.ipaddr.IpV4Address).IPAddressToString `
}
$PortalSummary += $CurrentPort
}
}
return $PortalSummary
}
Get-IscsiPortNumber | ft -AutoSize
in python I started to do something like this but I always get errors while running it:
import wmi
test = wmi.WMI(namespace='root\wmi',moniker='msiscsi_portalinfoclass')
which say:
Traceback (most recent call last):
File "C:\Users\rg\Desktop\diskchecktptest\getnicids.py", line 2, in <module>
test = wmi.WMI(namespace='root\wmi',moniker='msiscsi_portalinfoclass')
File "C:\Python27\lib\site-packages\wmi.py", line 1290, in connect
handle_com_error ()
File "C:\Python27\lib\site-packages\wmi.py", line 241, in handle_com_error
raise klass (com_error=err)
wmi.x_wmi: <x_wmi: Unexpected COM Error (-2147217406, 'OLE error 0x80041002', No
ne, None)>
I hope somebody with some knowledge on this subject can enlighten me
Source: (StackOverflow)
OK I have a lab setup, I have a Freenas server iscsi setup with Chap setup for discovery and mutual chap for targets.
Here are the requirements:
Implement CHAP security
One-way CHAP for discovery
Two-way (Mutual) CHAP for targets
I can connect and discover sucessfully with two esxi servers, windows 7, windows 2003, 2008, and 2012
Centos can see the discovery list, but when trying to connect with :
iscsiadm --mode node --targetname iqn.2015.lab.com:centos --portal 192.168.1.60:3260 --login
the terminal outputs:
no records found
Here is my iscsid.conf, I left the comments in on the Chap section, but removed it for the rest as it is just so large:
iscsid.startup = /etc/rc.d/init.d/iscsid force-start
node.startup = automatic
node.leading_login = No
# *************
# CHAP Settings
# *************
# To enable CHAP authentication set node.session.auth.authmethod
# to CHAP. The default is None.
node.session.auth.authmethod = CHAP
# To set a CHAP username and password for initiator
# authentication by the target(s), uncomment the following lines:
#node.session.auth.username = group7
#node.session.auth.password = passwordpassword
# To set a CHAP username and password for target(s)
# authentication by the initiator, uncomment the following lines:
node.session.auth.username_in = group7
node.session.auth.password_in = passwordpassword
# To enable CHAP authentication for a discovery session to the target
# set discovery.sendtargets.auth.authmethod to CHAP. The default is None.
discovery.sendtargets.auth.authmethod = CHAP
# To set a discovery session CHAP username and password for the initiator
# authentication by the target(s), uncomment the following lines:
discovery.sendtargets.auth.username = group7
discovery.sendtargets.auth.password = passwordpassword
# To set a discovery session CHAP username and password for target(s)
# authentication by the initiator, uncomment the following lines:
#discovery.sendtargets.auth.username_in = group7
#discovery.sendtargets.auth.password_in = passwordpassword
node.session.timeo.replacement_timeout = 120
node.conn[0].timeo.login_timeout = 15
node.conn[0].timeo.logout_timeout = 15
node.conn[0].timeo.noop_out_interval = 5
node.conn[0].timeo.noop_out_timeout = 5
node.session.err_timeo.abort_timeout = 15
node.session.err_timeo.lu_reset_timeout = 30
node.session.err_timeo.tgt_reset_timeout = 30
node.session.initial_login_retry_max = 8
node.session.cmds_max = 128
node.session.queue_depth = 32
node.session.xmit_thread_priority = -20
node.session.iscsi.InitialR2T = No
node.session.iscsi.ImmediateData = Yes
node.session.iscsi.FirstBurstLength = 262144
node.session.iscsi.MaxBurstLength = 16776192
node.conn[0].iscsi.MaxRecvDataSegmentLength = 262144
node.conn[0].iscsi.MaxXmitDataSegmentLength = 0
node.conn[0].iscsi.HeaderDigest = None
node.session.nr_sessions = 1
node.session.iscsi.FastAbort = Yes
Any help is appreciated. Thank you.
Source: (StackOverflow)