Capacity calculation and planning using X-RAID2 with Dual redundancy

I have a RedayNAS Ultra 6 Plus that I initially configured with 6 2TB drives X-RAID2 and Dual redundancy. This gave me 8TB of space (which I never took the time to even try and understand why).

Recently I started getting SMART+ warnings about one of those drives and decided to replace it.
I remembered this animation of extending X-RAID2 and because My drive was already at 87% I decided to buy not one but two new 3TB drives expecting my capacity to grow by an additional 1TB.

As it turns out this was not the case.

At first I thought there was an issue with the expansion process not being triggered triggering so I tried to check the check the box titled "Check and fix quotas on next boot. This process can take several minutes to more than an hour depending on disk capacity and the number of files on your volume." as was recommended somewhere but this also did not work.

finally reading through the forums I found the following explanation:

X-RAID2 dual-redundancy uses RAID-6 layers. RAID-6 layers require a minimum of four disks.

So how do you calculate capacity for a given set of hard drives configured for X-RAID2 DR (Dual redundency) ?

first of all - you MUST have 4 drives to use Dual redundancy.
now, look at the smallest drive and suppose it has size S1.
count how many drives have at least S1 (lets call this N1).
if N1>=4 then add to expected total capacity S1*(N1-2).
now repeat with "un-accounted-for space" on all drives.

e.g.
Suppose you have the following drives 1TB , 1TB , 2TB , 2TB, 3TB , 4TB
The smallest one would be 1TB and we have 6 drives with that "un-accounted-for" space on them,
so 1TB*(6-2) yields 4TB and leaves you with 0TB,0TB,1TB,1TB,2TB,3TB "un-accounted-for" space.
next we consider another 1TB layer on the last 4 drives  that yields 1TB*(4-2) = 2TB more and leaves you with 0TB,0TB,0TB,0TB,1TB,2TB "un-accounted-for" space.

So what if you now want to get more space? the first layer is "full" (i.e. it uses 1TB of all 6 drives) but the second layer can be expanded in several different ways with the minimal one being just expanding one of the first two drives by an additional 1TB  and thuse getting 1TB*(5-2) = 3TB for that layer.

This was about calculating... you should now be able to do some planning by your self.

As for me, after understanding the situation I am at 2TBx4+3TBx2 yielding  8TB I thing the future expansion path would be by first replacing two more of the 2TB drives to 4TB each, this will give me an additional 2TB (try to calculate it yourself - 2TB,2TB,3TB,3TB,4TB,4TB) - then continue like this to each time replace the small pair to become the new largest pair.

The advantage is that from now on I will only need to replace two HDs each time to get additional space.
The disadvantage is that I some of the additional space I pay for will only be used when I buy the next pair of HDs.

solved:Hardware virtualization activated in bios but still does not work

If you happen to need hardware virtualization you might encounter what I have.

I went to the BIOS, changed the settings of Intel-VT to enabled, rebooted and VMWare still insisted that hardware virtualization is disabled.

turns out that a reboot is not enough...

you must POWER DOWN your computer after making this change in the bios,

only then will it recognize that hardware virtualization is active.

I hope this will help some one some time.

feel free to say I if it helps you anytime in the future.Publish Post

Eyal

Configuring custom dynamic DNS (DDNS) agains ENOM on DD-WRT

I was messing around with my linksys trying to set up QoS and ended up resetting it,
loosing my DDNS settings and having to recreate them.
Took enough time for me to sit donw and write this down so that (my) next time would take less.

so here goes:
you would ususally have a single domain (e.g. dyn.yourdomain.com) that you would change dynamically and then have other domains that would map to it using CNAME entries.

If you have dynamic dns services provided by enom (I got mine when I moved to enom from registerfly) and you want your dd-wrt router to do the updating:

1) go to the web interface of your roter - ususally via 192.168.1.1
2) select the setup tab and the DDNS sub tab
3) in the DDNS Service combo choose Custom
4) DYNDNS Server should be set to dynamic.name-services.com
5) for some reason the UI does not allow you to leave out the User Name and Password so I just push _ in each of them
5)Hose Name should be set in our example to dyn.
6) URL should be set to /interface.asp?Command=SetDNSHost&Zone=yourdomain.com&DomainPassword=HEX_PASSWORD_YOU_GOT_FROM_ENOM&HostName=


[Update Aug 11th 2009: based on comment by Greg Bray]
6) URL should be set to /interface.asp?Command=SetDNSHost&Zone=yourdomain.com&DomainPassword=DOMAIN_ACCESS_PASSWORD_YOU_SET_UP&HostName=

To set up the DOMAIN_ACCESS_PASSWORD_YOU_SET_UP use the Domain Access Password field on the General Setting page of the Enom Control panel.

Greg was also kind enough to mention that:

Also, the URL that you listed will use the outgoing ip address as the value for updating the dns record. This should work in most cases, but if you want to specify the IP address for the record you need to include &Address=NEW_VALUE in the update url.

[/Update]

the hostname(5) itself will be appended to the DYNDNS Server(4) and URL(6) to create the entire URL for the request.

if you wish you can set the Additional DDNS Options field to --verbose 5 - this will show a much more informative output in the DDNS Status frame below after you press "Save Settings".

Done ?
now go to the Administration tab and select "Backup" to back up your configuration.

one last information bit:
Dynamic DNS updates FAQ on ENOM
http://www.enomcentral.com/help/faq_dynamicdns.asp