software raid 0 or LVM

[Viktor Balogh]

>> Use lvm with distributed stripes?
> i didnt understand this. i normally create LVMs with default options.

LVM is capable of doing a RAID 0, aka. striped volume, he meant this. But as your LUNs are already striped between the physical storage disks, I don't think that you would profit anything by creating a striped LV. So, stay with the default values! ;)

To read about LVM striping, here is a doc:

http://docs.hp.com/en/B2355-90672/ch08.html

[Jayakrishnan G Naik]

Hi

No need to use striping here as the luns are of different size. And LVM is the best solution for you here as the Redundancy are met at the storage level.

You can create a volume group with these two luns and create a logical volume which is pretty simple.

Software raid levels are available but that don't have the flexibility that lvm can give.

Regards
Jayakrishnan G Naik

[iinfi1]

i created a LVM out of sda2 and sdb1.

/dev/sda1 55G 41G 6.7G 86% /ora1
/dev/sda2 48G 46G 1.5G 97% /ora2
/dev/sdb1 101G 78G 16G 83% /ora3

after a few hours the mountpoint on sda1 started misbehaving and since the storage admin didnt bother to create zoning in eva, it affected all the servers.
we restarted the server in single user mode and removed the mountpoints from /etc/fstab
and restarted the server. now the mountpoints from SAN are not mounted.

is there any relation to me creating an LVM out of sda2 and sdb1 and the mountpoint on sda1 being affected.

[Viktor Balogh]

Hi,

>after a few hours the mountpoint on sda1 started misbehaving

What do you mean by 'misbehaving'? How could a _mountpoint_ misbehave???

Regards,
Viktor

[iinfi1]

sorry for not being clear ...
df -h was showing the mount point, but i could not list the contents. it simply disappeared.

have a look at the status of the server in the image attached. something to do with this server and the storage but i dont know what.

just before this happened i had created that lvm which i was talking about and our dba was cloning the prod db on the lvm.
i want to know whether creating of an lvm of the two partitions i mentioned, caused this issue?

/dev/sda1 55G 41G 6.7G 86% /ora1
/dev/sda2 48G 46G 1.5G 97% /ora2
/dev/sdb1 101G 78G 16G 83% /ora3

sda1 and 2 are part of one block device and sdb1 is another.
sda2 and sdb1 are PVs of my LVM. would such a configuration have caused a direct impact on the sda1?
did that result in the server throwing too many I/Os on the SAN (with no zoning) affecting all servers?
i know my explanation will appear vague. but has anyone faced a similar situation.

[Alzhy]

Sir.

Do you know what you are doing?

/dev/sda1 55G 41G 6.7G 86% /ora1
/dev/sda2 48G 46G 1.5G 97% /ora2
/dev/sdb1 101G 78G 16G 83% /ora3

You claim the above to be LVM - it is not sir unless it is just lost in translation.

If the above is indeed true that you have mounted filesystems on individiual disks - then question will come out and mine will be -- are the above disks SAN (eva4400) disks!? Coz if they are -- then you are NOT using multipathing!!

I suggest you take a very deep breath and let us go over your problem again -- if you still want our help.

Shukran.

[iinfi1]

i will start again
/dev/sda1 55G 41G 6.7G 86% /ora1
/dev/sda2 48G 46G 1.5G 97% /ora2
/dev/sdb1 101G 78G 16G 83% /ora3

above was my partition before i did the LVM config.
i did the LVM config after umounting /dev/sda2 and /dev/sdb1
i am not sure about the multipathing thing as i didnt do the setup.
my question was
sda1 and sda2 are part of one block device and sdb1 is another.
sda2 and sdb1 are PVs of my LVM. would such a configuration have caused a direct impact on the sda1?
i was unable to access sda1 at all and the state of the server was as shown the JPEG in my previous post.
i have now restarted the server after disabling the SAN moutpoints from /etc/fstab
and now i have manually jus mounted /dev/sda1. all data is intact.

[iinfi1]

pardon my ignorance,
how do say multipathing is not working correctly?
infact an HP consultant who came yesterday told us the people who did the configuration (HP) have not done the cabling correctly!!

[Alzhy]

.ae

hmmmm... HP should have excellent people there.

I guess get your act together sir. Chase whoever manages the EVA4400 to make sure it is "zoned" and / or config'd correctly if you think or others think it is zoned incorrectly.

/dev/sdNN are not the correctr names of EVA multipathed devices!

[TwoProc]

Re: Hello,

I'm with Alzhy: I don't see the point for setting another level of striping on the top of the RAID5-out-of-the-box. The throughput was already maximalized with RAID5, why overcomplicate it with another level of striping?

If you go and read the paper on SAME for big arrays that are already striped you'll see that there is immense value in using Distributed striping on hardware Raid arrays, as I've indicated. Like I said before - feel free to ignore.

As far as something being "already maximized" because it's raid 5. Well, you've just missed the big truck leaving town. There's so many other things to consider - balance I/O, balancing cards, balancing controllers, balancing san ports, NOT using RAID 5 in certain areas. Just saying that something is "maximized" because it's R5 is just leaving so much other stuff out. Which is exactly what his question was, about the other things out there.

No one should ever consider:
"Already Maximized" = "R5"

That statement says a lot more about what's not being considered in setup than what has been.