Using a Thecus NAS to its full potential with 2TB Win XP limit

[ninja]

Hello all,

First some background ...

PC side: 4 Win XP pc's (desktops + laptops), 1 x linux server, 1 x Win Vista laptop, 1 x mediagate
Thecus side: N5500 with 3 x samsung 1.5tb disks in a raid 5 config
Usage: Full backup of the above pc's, backup of multimedia, high res photos and video (photographer grade), mediagate etc

Bascially with the above I want to be able to utilise the enitre space made available on the RAID5 array, and add more disks later to expand. Ive chosen RAID5 for the redundancy as some files I probably dont need RAID5 if they are on the local pc, but for others including the high res photos and videos the thecus will be the only place the file is stored I would like the redundancy RAID5 provides.

So I have usable disk space for RAID of 3TB in a raid 5 config with the above .... but as far as I can see I am stuck with creating a single raid store < 2TB in size so WinXP can read / see it properly etc for backups, moving files around.

So I waste 1 TB of space .... and adding more disks is a waste of time as I only have two more slots and I need 3 to run another RAID5 array?

Also found out that I cannot have two RAID arrays of 1.5tb each running on the same 3 disks to use up the 3TB of space, and I while I could run 2TB of RAID5 and 1TB of iSCSI etc .... I will enevitably have more than 2TB of data that I will want backed up on a RAID5 array .... and the 1TB of iSCSI isnt replicated.

Can anyone let me know what my options are or provide any tips .... am I missing something?

[unclebobuk]

Hi,
I don't think you have an issue here. I believe the 2TB limit refers to filesystems created locally within XP (directly attached disks). If you accessing this via Samba/CIFS (as a windows share) these limits do not apply. I've got a 3.5tb share and can access it without issue from Windows XP (32 bit), Windows 7 (32 bit) and Mac OSX.

I guess if you're using iSCSI then the rules will apply...

Here's a more technical explanation (ripped from an MS forum)

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Yes, the XP-32 2 TiB limit is per-volume,There is a limit to the total number of sectors that a MBR partition table can have. With the standard 512K sectors, that limit is about 2TB, which would be inclusive of all partitions on the drive/array. The partition table has a count of the start and end sectors of each partition, so you can not create a 2TB partition and then have another beyond that on a larger than 2TB drive. Unless of course your OS can see a GPT partition. As far as Windows goes support for GPT partitions started with XP64 and server 2k3.
The 2TB volume size is a limit of the MBR partition - not Vista, XP, NTFS, Linux, 32bit, 64bit, etc, etc. The MBR structure only supports 4 primary partitions (more if you use extended volumes), the GPT partitioning scheme can support up to 128 partitions in Windows. Three common means of exceeding the 2TB limit in a single volume is:

1. RAID controller that supports LBA64.
2. Use dynamic disks or an application like unRAID or Windows Home Server that essentially aggregates your physical volumes by using dynamic volumes. I personally feel this is the least desirable and secure method.
3. Use GPT volumes.

You can combine two of the items above as well -
Only Windows XP x64, Server 2003 SP1 and all versions of Vista can read/write GPT partitions, and only Vista systems with EFI can boot from GPT partitions. That's usually not an issue, though, since not many people boot from their large data arrays.


--

cheers.
Bob.

[ninja]

Hello Bob,

Thanks .... using network shares hosted on the Thecus N5500. Most if not all the space will be used as a raid5 share ... only some small space for USB etc. No need for iSCSI.

I got more confused when reading things like the user comment on the Thecus support website esupport.thecus.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=4&nav=0 re limitations .. see the user comment down the bottom. And then when google'ing ... everything mentions the mbr / 2tb limitation but I guess its all related to hdd's installed in the pc etc, and iSCSI like you mention.

So if I am using network shares ... I dont need quota and I want to one day go beyond 8TB that EXT3 supports .... should I start with XFS in the first place? ... looking at the table esupport.thecus.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=136 ... any issues re XFS versus EXT3 ?

mind you 5 2tb drives @ raid5 is only 8tb .... but I could imagine trying to move almost 8tb of data in the future is a nightmare, and im hoping that in a year or two we have > 2tb SATA drives that the thecus can support.

Just trying to future proof the setup now to try and cause the minimum amount of pain in the future

PS: the forum wouldnt let me post URL's until I have posted 5 times .... so had to paste raw text