tshin1
2 Bronze

One virtual disk with two iscsi initiators connection on AX 4-5i

Dear,

I have a AX4-5i and configure only one virtual disk to assigned two iscsi initiators/server. My plan was to access one disk using two iscsi server expecting to see the same file system. I managed to mount a disk on two server as /dellarray. However, when I write on disk I realize I am not see the same file system. It appeared to show athat they do not share the file system although PowerPath showed the same device ID. Where I should be focusing to resolve this? My first question is though that whether this is even possible. I am using Navisphere extress for EMC storaage side and I am using two iscsi initiator from linux redhat 5.  Thanks.

Regards,

Taeksu Shin

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7 Replies
MorbidAngel1
3 Silver

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Hi,

Did you try mounting the File system again after writing on node 1.It should see the same data on node 2 after remounting.

tshin1
2 Bronze

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Dear Arifur,

Here is what did.

node1 and node2 is assigned to the same virtual disk, vd1.

At node1,

node1> mkfs.xfs –f /dev/emcpowerc

meta-data=/dev/emcpowerc isize=256 agcount=32, agsize=16777216 blks

= sectsz=512 attr=0

data = bsize=4096 blocks=536870912, imaxpct=25

= sunit=0 swidth=0 blks, unwritten=1

naming =version 2 bsize=4096

log =internal log bsize=4096 blocks=32768, version=1

= sectsz=512 sunit=0 blks, lazy-count=0

realtime =none extsz=4096 blocks=0, rtextents=0

node2> mkfs.xfs /dev/emcpowera

mkfs.xfs: /dev/emcpowera appears to contain an existing filesystem (xfs).

mkfs.xfs: Use the -f option to force overwrite.

node2> mkfs.xfs –f /dev/emcpowera

meta-data=/dev/emcpowera isize=256 agcount=32, agsize=16777216 blks

= sectsz=512 attr=0

data = bsize=4096 blocks=536870912, imaxpct=25

= sunit=0 swidth=0 blks, unwritten=1

naming =version 2 bsize=4096

log =internal log bsize=4096 blocks=32768, version=1

= sectsz=512 sunit=0 blks, lazy-count=0

realtime =none extsz=4096 blocks=0, rtextents=0

node1> mount –xfs /dev/emcpowerc /dellarray

node2> cd /dellarray

node1> dd if=/dev/zero of=node1.img bs=8k count=256k

node1> ls

node1.img

node2> mount –xfs /dev/emcpowera /dellarray

node2> cd /dellarray

node2> dd if=/dev/zero of=node2.img bs=8k count=256k

node2> ls

node2.img

Here I do not see the node1.img which generated at node1.

I am suspicious on the mkfs.xfs –f options but without –f option, mkfs does not works.

Thanks.

Regards,

Taeksu

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tshin1
2 Bronze

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Dear Arifur,

Your statement is correct. After remounting of disk at node1, I can see the file created at the node2.

So this indicates one virtual disk I/O shared by two server needs to have some kind of disk clustering

software to see the same file structure?

Regards,

Taeksu

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MorbidAngel1
3 Silver

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Yes...You are right.It should be maintained by some File System Service(NFS,GFS) or Cluster Service.....

kelleg
5 Rhenium

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Whenever you attache more than one server to the same disk (or LUN), you MUST have some type of clustering software to arbitrate who has access to the data at any one time otherwise you will corrupt the data on the disk.

Please remember to mark the question as Answered when you get the correct or best answer. Also, please award points to the person providing the best answer.

glen

tshin1
2 Bronze

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

Thanks for updating on this.

Regards,

Taeksu

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SKT2
4 Beryllium

Re: One virtual disk with two iscsi initiators connection on AX 4-5i

what version/update of rhel5 are you using; after a certain version level you get teh red-hat cluster suite along with the OS ( like bundled and free with os) . In this cas you may share them and see the data, but needs to be used by only one node at a time. For concurrent access you will needs GFS,OCFS like features

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