Sunday, 26 February 2012

Setting Modified Date/Time on TrueCrypt files on ReadyNAS shares so they Backup

Further to my last post regarding offsite backups. I've noticed that backup solutions can have a hard time with TrueCrypt containers, as they do not by default change the modified date on the file, which means that the backup program then has to scan a big fat file for byte level differences or a CRC check or some such (and that's assuming your backup program is clever enough to do anything other than a modified date check).

The general solution for this is to change a setting in TrueCrypt - disable "Preserve modification timestamp on file containers".

This probably won't work if your TrueCrypt file is stored on a ReadyNAS network share though - it didn't for me anyway.

A simple solution (on Windows 7) is to run a batch script that uses PowerShell to modify the date/time before your backup runs (either as a step in the backup software itself, or just as a daily scheduled task).

The ChangeTCModifiedDate.bat file would look something like this:

powershell $(get-item \\ReadyNASBox\myfolder\mytruecryptfile.fil).lastwritetime=$(get-date)

Of course, this ReadyNAS problem isn't restricted to just TrueCrypt, see here:

Online (Offsite) Backup Solutions - A Brief Test

I wanted to do some offsite backups and I have about 85GB to backup. I tested out some of the popular solutions (I'm based in the UK, and of course YMMV):

Carbonite = v.slow uploads ~300kbit/s - price £3.49/month for unlimited storage*
CrashPlan = v.slow uploads ~340kbit/s - price £1.89/month for unlimited storage
SpiderOak = slow uploads ~700kbit/s - price £6.30/month for 100GB
GoDaddy = fast uploads ~5Mbit/s - price £1.59/month for 100GB
Mozy = very fast uploads ~8Mbit/s (uk server) - price £7.99/month for 125GB **
iDrive - fast uploads ~6Mbit/s - price £3.20/month for 150GB
OpenDrive - max file size is only 1GB for cheapest plan, so didn't test it.

* Note that it seemed to mysteriously slow down to 300kbit/sec only after I had exceeded 3GB of storage, before that it was much faster.
** Mozy may actually be faster than that even, as my upload connection maxes out at ~8Mbit/sec.

Prices are obviously subject to change - correct at the time of posting.

Some backup solutions have versioning - but that will just use up your storage space, and you should be doing that with your local backup solution, not your offsite solution.

I found that some of the software was exaggerating/misreporting its real upload speed. So I had to use a "desktop gadget" called Network Meter to monitor activity.

Unsurprisingly, I've gone with GoDaddy for now due to the solid upload speed/price combination. (No I haven't - see update at the bottom!) The downside is that it's not quite as quick as Mozy, and the backup software is very basic.

Generally I have noticed that when it comes to online storage of any kind (backups/photos/ftp/web/email) - the web hosting companies are always some of the cheapest.

Now if I could just find a UK webhost that was cheaper than GoDaddy and and had a better software client. There's always room for improvement.

I should say though, that despite the GoDaddy client being very basic, it puts hardly any stress on the system while I am using it, which is worth a lot to me. The other clients tend to do advanced file-diff comparisons to "save you space" which stress your CPU. In reality, a simple modified date/time check is all most users need, and its not really to save you space as much as save them bandwidth by only uploading file differences at the byte level (or some such). Your CPU time costs nothing to them, but you have to pay the power bill for it. So all round, I'm quite liking the GoDaddy solution atm, but it's early days.

What's interesting about the Mozy client is that it seems to detect if a file you are uploading already exists on their servers in someone else's backup, and if so, it doesn't upload your file, but just creates a reference. This is clever, but... it still counts against your usage allowance!!  Cheeky.

UPDATE: since I wrote this, I have discovered that the maximum file upload size for GoDaddy online storage is 1GB (despite the fact that it says file size is Unlimited on their product page!). Some of my files are bigger than that, so I've switched to iDrive, and I've got to say I'm pretty happy with it. I upload several gigs/day to iDrive with no problems.