Date: Tue, 12 Jan 1999 22:09:49 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Mattias Pantzare <pantzer@ludd.luth.se> Cc: current@FreeBSD.ORG Subject: Re: Enabling Softupdates with symlinks? Message-ID: <199901130609.WAA07980@apollo.backplane.com>
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:
:Realy? Why would the power dissapear from the HD when I press the _reset_
:button?
:
:Is it not a big propability that the HD is writing on a sector at a power
:failure on a loaded server? The disks usualy survive a power failure with no
:problems att all.
If the drive happens to be in the middle of a write during a power failure,
it is virtually guarenteed to loose at least one sector. Seagates will
tend to loose one or two. Quantums will tend to loose hundreds of
sectors - we've completely destroyed quantums that way. Occassionally
a power failure will destroy the motherboard but not the platter - that
has happened to us on two occasions, where the disk's motherboard is dead
and we can pop it and replace it with another and bring the drive back
to life well enough that we can read the data off it.
Typically, a heavily loaded server is weighted towards doing more reads
on a drive then writes. A power failure during a read is usually
non-destructive.
Most of the time power failures do not damage the disks. But since it's
happened to us on a number of equations, the chances are obviously not 0.
-Matt
Matthew Dillon
<dillon@backplane.com>
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