A question that's always concerned me with Google's Gmail and all other large-mailbox services is how well-protected your data is. I recall an interview with a Hotmail developer or PM (was it Omar Shahine?) in which backup and restore were mentioned.
I suspect that Google are not actually backing up mailboxes. I think they're relying on multiple redundancy in their server farm. In a multiple-redundancy system, a coding error can still cause you to lose or corrupt your data, which is why you should back
up even if you do have a RAID system.
Software people are pretty good in the what-if-everything-goes-right case. We're not good at the what-if-something-goes-wrong case.
For this 30GB email provider, tape backup is not an option. A sensible programme of backups would have to involve IDE hard disks (generally harder to hot-swap than SCSI but much cheaper per gigabyte). Let's say that a nightly backup is done, and we keep two
weeks of backups since the user may not notice a problem immediately. Currently the most cost-effective drives on a price-per-gigabyte basis are 250GB - a Hitachi drive this size costs £56.16 (excluding VAT) from Dabs. You can fit 8 (and a third) mailboxes
per disk - let's round up and say that you can fit 25 mailboxes onto 3 disks.
The capital cost outlay to back up 25 users is then over £2,300 for 42 disks (plus obviously the cost of the systems to install those disks in - say you can put seven drives in a machine, that's six machines required - ouch) Then there's the ongoing cost of
disk failures, which will happen. I'm not sure what the MTBF is but we had a 120GB drive fail recently after a little over than 12 months constant use.
I can't find out what this site's backup policy is because the site is currently giving a MySQL error.
[EDIT:] I think that explains why Hotmail is still only offering 250MB mailboxes for free users though, and why they've been slow to upgrade. [/EDIT]
2 remarks, Mike:
- When you buy those disks in quantities, you get better prices
- You can easily fit 10 harddrives in commodity 2U systems, just by using the standard mainboard connectors (6x SATA and 4x IDE) found on about every decent board nowadays. If you add one or more (cheap) controller cards, you can expand that number to even
You can fit 12 disks in most 2U chassis, and 30 disks or so in the larger 4U or 5U chassis.
That being said, backup costs remain substantial of course
Is 30gigs.com an Microsoft property?
Why are all these invite request showing up here? Wallop I can understand...however this?
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