NV+ Factory Reset

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NV+ Factory Reset

Postby lordgibbness » Thu Nov 18, 2010 6:21 am

Can I ask if anyone knows why a factory reset is required after installing fw v4.1.7 before you can use the new-style 4kb hard disks? Is it to set the partition start at sector 64 rather than sector 63?

If this is so, does anyone know if I can just put the hard disks into a linux machine and use gparted (or something similar) to move the partitions forward by one sector?

A factory reset would mean that the disks are completely wiped-out and would involve copying all the data off and back on again. At the NV+ copy speed of 3-4MB/sec this would be quite tedious for 1TB of data (and require lots of storage space).

Anyone know exactly what the factory reset will do and if the workaround suggested would work, or if there is another way?

Thanks,
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Re: NV+ Factory Reset

Postby mdgm » Thu Nov 18, 2010 2:08 pm

You need to do the factory reset. The partitions are aligned for 512-byte disks on pre-4.1.7 firmware. If it was possible to get 4k sector alignment without a factory reset on Sparc ReadyNAS NetGear would've made it possible.

1. Backup your data
2. Verify backup is good.
3. Update to 4.1.7 (if haven't already): http://www.readynas.com/RAIDiator_4_1_7_Notes
4. Do a System > Config Backup
5. Factory reset
6. Restore Config Backup
7. Restore data from backup
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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 3:21 am

That might be an over simplification of the situation though. Any product marketed as a black box for consumers will suggest backup/reset/restore steps but the only difference at the lowest level should be regarding partitions, right?

The factory reset with the new firmware probably just sets the partitions at different sectors during the formatting stage. Any linux gurus out there who know more about this?

thanks,
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Re: NV+ Factory Reset

Postby beisser » Fri Nov 19, 2010 4:25 am

any manual tempering with the partitions will most likely cost you your support though.
im not sure that thats worth it when you run into trouble.
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Re: NV+ Factory Reset

Postby mdgm » Fri Nov 19, 2010 4:47 am

The Sparc ReadyNAS use hardware accelerated RAID. NetGear extensively tested trying to migrate from 512-byte to 4k sector partitions by hot-removing (remove while NAS is on) then hot-adding (add while NAS is on) each disk one by one and couldn't come up with a workable solution (in fact adding 4k sector support is a major reason 4.1.7 took so long). If they can't get it to work, I doubt you'd be able to.

Remember that Sparc firmware was first written 6-7 years ago, back when 4k sector support was still seen as an issue in the distant future.
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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 6:52 am

From what I have read from other threads (some very useful info provided by forum member Zappes) the NV+ is actually a software RAID - the disks are formatted in ext3. Prior to radiator v4 they used to be 4kb block sizes (filesystem formatting - not harddisk formatting here) but this changed to 16kb block sizes from radiator v4.

The solution you are mentioning is not exactly as the same as I am talking about. The automated solution would be a lot harder to develop as you would have different disks 'live' at different times with different sectors starts for the partitions.

The manual solution I am suggesting is to unmount all disks then move each partition on each disk forward one sector (if this is the issue) starting with the partition at the end of the disk and moving to the first partition.

I realise that software support would be denied but I'm not worried about that as I wouldn't make use of software support from Netgear.

I'm sure this is possible as at the end of the day, it is only an ext3 hard disk with various paritions defined...
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Re: NV+ Factory Reset

Postby mdgm » Fri Nov 19, 2010 6:56 am

It's not possible. The hardware accelerated RAID makes use of the CPU. It just isn't possible to realign the partitions to 4k sectors when they were aligned for 512-byte sectors without wiping and starting afresh. If it were possible NetGear would've implemented a solution to do it.
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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 6:59 am

mdgm you are far too defeatist. Of course there's solutions for this kind of thing. It is SOFTWARE raid and the disks that can be mounted in linux (16KB blocks may require ext2fuse though). Just because netgear didn't create an automated solution doesn't mean it can't be done without losing data!
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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 7:02 am

Also to add further information to this thread - I don't actually have a 4kb hard disk (I have 2 x 1TB [512-byte] hard disks). But I would like to have the option of adding a 4kb hard disk in the future without doing a factory reset (which just does the partitioning differently - sector start position).
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Re: NV+ Factory Reset

Postby mdgm » Fri Nov 19, 2010 1:31 pm

It does use Software RAID in that you can recover data using a Linux PC, but the way hardware acceleration is done in Sparc ReadyNAS means that a factory default is required to go from 512-byte to 4k sector alignment.
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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 3:52 pm

I don't understand what you mean? The problem with 4kb block-size hard disks is that partitions are misaligned from my understanding? Is this not the problem? I'm really after more technical details regarding this. What would 'hardware accleration' have to do with it?

beisser, do you know any of the details behind the partition changes that were made in v4.1.7?

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Re: NV+ Factory Reset

Postby lordgibbness » Fri Nov 19, 2010 5:45 pm

On a sort of relatated topic - I was interested in the ext3 block size that my disks were formatted as.
Code: Select all
command tune2fs -l /dev/hdc1 | grep -i 'block size'
Block size:               4096
tune2fs -l /dev/c/c | grep -i 'block size'
Block size:               4096

This is the standard ext3 block size in use on every x86 linux system (4kb). It is also the block size the ReadyNAS used to use with firmware v3.x installed (and remains when upgraded to v4.x without a factory reset).

Now I know this used to be a contentious issue - the SPARC readyNAS after version 4.x changed the block size to 16kb, which meant that the disks weren't readable in x86 systems which made data recovery expensive or difficult. There are threads around whre users were reformatting the partitions as 4kb block size to allow them to read the disks in their linux systems and thus be able to restore their data if their NAS unit died (otherwise you'd need a SPARC system or spare NAS).

But things have moved on a little now so you can use apps like ext2fuse to read the 16kb harddisks on x86 linux systems...

My question therefore is - what is the performance difference between using 4kb and 16kb blocks on the 4.x firmware? Are there any test results to hand? If 16kb really is faster and it is also possible to mount the filesystem on x86 linux systems, then it might be worthwhile doing a factory reset. On the other hand if ext2fuse or the other methods don't work with 16kb formatted disks well, then maybe it is better for me to remain on the commonly use 4kb sectors.

Any thoughts?
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Re: NV+ Factory Reset

Postby mdgm » Fri Nov 19, 2010 7:28 pm

lordgibbness wrote:I don't understand what you mean? The problem with 4kb block-size hard disks is that partitions are misaligned from my understanding? Is this not the problem? I'm really after more technical details regarding this. What would 'hardware accleration' have to do with it?

Take a look at yoh-dah's explanation. The X-RAID engine uses hardware acceleration. Whilst the x86 ReadyNAS can rely on their fast CPUs, Sparc ReadyNAS have slower CPUs so the RAID needs to rely more on specialised hardware than x86 ReadyNAS. It's still software RAID, just hardware accelerated. As a result realigning from 512-byte partitions to 4k (8*512-byte) partitions isn't possible without a factory default on Sparc ReadyNAS.
lordgibbness wrote:My question therefore is - what is the performance difference between using 4kb and 16kb blocks on the 4.x firmware? Are there any test results to hand? If 16kb really is faster and it is also possible to mount the filesystem on x86 linux systems, then it might be worthwhile doing a factory reset.


There is a performance benefit. You also don't have a 5TB volume limit (requires manual expansion to get to 5TB on units last factory defaulted using 3.x). So not doing the factory reset would be pretty crazy. You'd have the block size issue (set upon volume creation) and the alignment for 4k sector issue to contend with.
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Re: NV+ Factory Reset

Postby lordgibbness » Thu Nov 25, 2010 3:48 am

Well, due to the fact that my NAS had the old ext3 block size - as well as the partition position problem - I decided to factory reset.

I had two 1TB disks in my NV+ at 91% full. I bought another 1TB disk and put this in my icybox which I used to back up my data ( using root ssh "nohup cp -a" so that it would run in background ). I also backed up my NAS configuration settings before factory resetting it.

I then reapplied my settings and copied the data back to the NAS. I then put the new disk in the array and left it to expand and I now have double the volume!

Online expansion was useful - but the performance doesn't seem to have improved on my 100MB LAN. I get 4.8MB/s download and 2.1MB/s upload. Is that comparable with other users on the Duo and NV+ ?

Thanks,
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Re: NV+ Factory Reset

Postby mdgm » Thu Nov 25, 2010 12:01 pm

On 100 Mbit (don't confuse Megabit with MegaByte) LAN you should be able to get about 10 MB/s. If you updated to a gigabit LAN then higher speeds may be achievable.

I'd suggest working your way through ReadyNAS Performance Expectations
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