[linux-lvm] Linux LVM performance using multiple iSCSI targets

[linux-lvm] Linux LVM performance using multiple iSCSI targets

[अनुज Anuj Singh]

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Hi,
I have a LVM performance related question.
Issue:
We have multiple iscsi-target machines say iscsi-target1, iscsi-target2,
iscsi-target3, iscsi-target4,....iscsi-targetN imported on iSCSI-initiator
Machine (FileServer).


I used lvm and created a logical volume say MyBigStorage on FileServer using
/dev/sda1, /dev/sda2, /dev/sda3..../dev/sdaN as physical disks (these are
the raw disks exported from iscsi-target machines).

Question:
1. Is it going to take more time if a client machine looks for a file which
is on FileServer's LVM MyBigStorage, as my LVM is created using multiple raw
disks using iscsi-targets.

2. What would be impact over performance (file lookup) in case we increase
more iscsi-target machines, and expand our MyBigStorage lvm using newly
attached iscsi-target disks?

3. The file system we are going to use is GFS or ext3 and the overall data
is between 4TB to 8TB.

4. Any other issue which you can suggest with above approach?

Thanks and Regards
Anuj Singh.

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[linux-lvm] Re: Linux LVM performance using multiple iSCSI targets

[Ritesh Raj Sarraf]

???? Anuj Singh wrote:

> 
> I used lvm and created a logical volume say MyBigStorage on FileServer
> using /dev/sda1, /dev/sda2, /dev/sda3..../dev/sdaN as physical disks
> (these are the raw disks exported from iscsi-target machines).
>
Is it only sda or sda/sdb and so on?

You should rather be using device IDs. I am not sure how PVs are scanned
during OS boot up. If names are hardcoded, you will be in trouble.
 
> 
> 4. Any other issue which you can suggest with above approach?
> 
You are not using dm-multipath for this setup?
Have you tested the current configuration with some of the iSCSI devices
made unavailable in between and exceeding the timeout period?

Ritesh
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