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iscsi storage on QNAP.

Fri Sep 07, 2012 12:28 am

Hi all we have about 10 customers to backup.

we have a server in a data centre with a Qnap attached 6TB of data available. what would be the best way to use the space for backup? one big drive or split into multiple drives.

Thanks in advance.
James.

Mon Sep 10, 2012 6:15 am

In my experience, you want as many disks in the array, with as much redundancy as possible. E.g. if it's a 8 drive unit, go for RAID6 with a hot spare.

Putting it all in 1 LUN means customers' data allocations can grow without having to worry about running out of room on the partition.

If you start splitting it into separate partitions you have more to monitor, and less you can do about it if 1 of the 5 customers you have on that partition starts taking all the space. At least with just 1 partition you throw more/bigger disks at it, and everyone benefits.

Out of interest, what QNAP model are you using? We had a couple that are about 3 years old now, and couldn't get the iSCSI stable on them (kept dropping the connection). Never did manage to find out if it was a Windows or QNAP problem. We ended up moving to IBM DAS devices.

QNAP

Mon Sep 10, 2012 10:25 pm

TS412U

I have created 1 big lun.

see how we go :)

Tue Sep 11, 2012 5:24 pm

Bob T Bunny wrote:Putting it all in 1 LUN means customers' data allocations can grow without having to worry about running out of room on the partition.

If you start splitting it into separate partitions you have more to monitor, and less you can do about it if 1 of the 5 customers you have on that partition starts taking all the space. At least with just 1 partition you throw more/bigger disks at it, and everyone benefits.


Completely agreed.

BUT, I'd use RAID10. Rebuild/Online capacity expansion times on large arrays and the degraded performance during those periods, and the potential for torn writes due to excessively high latency is unacceptable to me.

Tue Sep 11, 2012 9:23 pm

Most companies I have worked for all have used a majority of raid 5 for back up purposes.

Wed Sep 12, 2012 1:26 am

I agree with wwcrossww we have alot of qnaps running and we run all those in raid 5.

Tue Sep 18, 2012 11:39 pm

RAID 5 ???
In whcih universe?

Youre aware that Raid 5 is - with modern Disk capacities - no longer relyable
SInce it doenst make any sense of using SAS Drives , specially not on qnap, i expect at least 1tb drives there

you cant use raid 5 there anymore, its deprecated for at least 2 years now.
use raid 6 or better raid 10. you not gonna have much more benefit of raid 6 in a 7 drive array (you loose 2 drives plus 1 spare)
so you loose only 1 more drive in raid 10 but you got way faster rebuild,
and in worst case still a good chance of loosing more than 2 drives without data loss


that said i recommend not to use one big partition.
you may loose a little capacity but for upgrade, system shifts and so on its better to have multiple not that big.

its easier to copy or move or mangle.
thankfully ahsay can handle multiple data storages pretty well


also some little dirty trick.
if one partition is full but you need a little extra space for one account you can symlink a hiole backupset to another partition

i know its not the real fine english way but it does work well.


so that way youre not gonna loose much space by splitting them up and youre still able to mangle em if needed.

i would recommend not over 2tb each partition for several reasons
but better use 1tb. exacept you have all on 10gb/s otherwise you gonna have awefully copy times in case of upgrade your storage
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