How to safely maintain a status file

Christian Heimes lists at cheimes.de
Sat Jul 14 14:38:28 CEST 2012


Am 13.07.2012 03:52, schrieb Steven D'Aprano:
> And some storage devices (e.g. hard drives, USB sticks) don't actually 
> write data permanently even when you sync the device. They just write to 
> a temporary cache, then report that they are done (liar liar pants on 
> fire). Only when the cache is full, or at some random time at the 
> device's choosing, do they actually write data to the physical media. 
> 
> The result of this is that even when the device tells you that the data 
> is synched, it may not be.

Yes, that's another issue. Either you have to buy expensive enterprise
hardware with UPS batteries or you need to compensate for failures on
software level (e.g. Hadoop cluster).

We have big storage devices with double redundant controllers, on board
buffer batteries, triple redundant power supplies, special RAID disks,
multipath IO fiber channel links and external backup solution to keep
our data reasonable safe.

Christian





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