Author Topic: Terastation TS/XL Max Array Size?  (Read 79 times)

ILuvNips

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Terastation TS/XL Max Array Size?
« on: May 14, 2017, 12:17:49 pm »
I have a TS/XL Terastation which came with 4 2 Tb drives which I configured all 4 drives as a RAID5 array.

Having seen a few posts about upgrading the drives I decided to purchased 4 6Tb drives. I did the standard, removed disks 2, 3 and 4 and replaced them with the new 6Tb drives which all went wthout a hitch. I then replaced drive 1, again this was discovered without a hitch so the Terastation now reports that it has 4 6Tb drives installed.

The problem has come when I attempt to create a RAID array, when I select all 4 disks, it seems to create the array but then reports that it failed to load the array. Same thing happens if I create a RAID0 array using all 4 disks. RAID5 using only 3 of the disks works as does creating a RAID0 with only 2 disks.

So is there a max size array limit and if there is then is this 12Tb or 16Tb?

I can sort of make use of all 4 disks by using RAID10 but I really wanted max size with some redundancy which is why I wanted to create a RAID5 array.

ILuvNips

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Re: Terastation TS/XL Max Array Size?
« Reply #1 on: May 16, 2017, 09:12:07 am »
I'm replying to my own thread but... :)

Just in case it helps others I managed to find out that the version of Unix on the Terastation (2.6) has a max RAID array limit of 16GiB, the array would get created but would then fail to load. So I did some more reading and managed to get an SSH prompt to the NAS and have come up with a solution which I'll highlight below.

Essentially, the disks have to be formatted so that when used in a RAID5 array the max size must stay under 17,592,186,044,416 bytes.

So I prepared the disks in the normal, then connect to the NAS using Putty to get a command prompt and then did the following for each disk:

1) umount /mnt/disk[1,2,3,4]
2) parted /dev/sd[a,b,c,d]
3) print => to display current partition info
4) rm 6 => to remove partition 6 which is the xfs formatted data partition used to create the array
5) mkpart primary xfs 7172MB 5871GB => to create a new smaller sized partition
6) quit => to exit parted

1) mkfs.xfs -f /dev/sd[a,b,c,d]6 => formats the partitions to xfs
2) cd /dev
3) ln -s sd[a,b,c,d]6 disk[1,2,3,4]_6
4) mount /dev/disk[1,2,3,4]_6 /mnt/disk[1,2,3,4]

I then went back onto the web based GUI and created a RAID5 array using all 4 disks. For me the actual size of the partition I created I arrived at by trial and error, each time the creation failed, I'd connect via SSH and have a look at the log file in /var/log/messages which would report the size of the array.

The other thing to consider is that when reducing the size of the array, remember to work it out by dividing by 3 and not 4 disks as the data is effectively held by 3 disks and dividing by 4 meant that it took me a few more reiterations of the mkpart steps before the NAS would happily create and mount the array.

Currently I have a RAID5 array which is 16381.4GB in size, I'm still testing and I'm hoping that the monthly RAID scan that I've set to run doesn't flag up any errors but I'll deal with them as I encounter them.

Eastmarch

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Re: Terastation TS/XL Max Array Size?
« Reply #2 on: May 18, 2017, 05:05:43 pm »
Gasp, you rooted the box.

:)
**A single copy of data, even on a RAID array, is NOT a backup! Hard drive failure is not a question of IF, but WHEN! Don't take my word for it, take Google's!**