Re: Offtopic : Large hostings and colocations ?where?
On Fri, May 11, 2007 at 09:18:48AM -0700, Joerg Bashir wrote:
> With disks of this size, I have to chime in against RAID5 in any way. It is
> far too likely to lose a sector on two disks, and even if you had a hot
> spare to immediately start a rebuild onto, I've seen too many RAID5 arrays
> (especially SATA/PATA) go south.
I have no idea what kinds of disks you use but I haven't seen drives
fail very often. Well not since I stopped dealing with IBM/Seagate SCSI
drives.
How about raid6 then?
> The cost of mirroring the storage initially (either RAID1 or via rsync to a
> paired machine) will be dwarfed by what you spend on hosting/bandwidth/power
> and god forbid losing a R5 array.
>
> Also, when drives do go bad, not having to sift through parity to find
> what's recoverable is priceless.
>
> I might be Jaded, every day when I show up to work at least 1 drive has gone
> bad, sometimes 3. On this scale what in a previous life seemed
> statistically insignificant suddenly has real meaning.
How many thousands of machines do you deal with?
> 2 boxes with 4x500GB disks should cost close to $3K. Mirror the data, the
> services, etc... and sleep easy at night.
And how do you keep machines mirrored constantly? Having raid5 or 6 at
least means a single disk failure won't take down the machine and force
you to start up somewhere else.
--
Len Sorensen
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