Alberto Alonso wrote:
On Tue, 2007-10-30 at 13:39 -0400, Doug Ledford wrote:
Really, you've only been bitten by three so far. Serverworks PATA
(which I tend to agree with the other person, I would probably chock
3 types of bugs is too many, it basically affected all my customers
with multi-terabyte arrays. Heck, we can also oversimplify things and
say that it is really just one type and define everything as kernel type
problems (or as some other kernel used to say... general protection
error).
I am sorry for not having hundreds of RAID servers from which to draw
statistical analysis. As I have clearly stated in the past I am trying
to come up with a list of known combinations that work. I think my
data points are worth something to some people, specially those
considering SATA drives and software RAID for their file servers. If
you don't consider them important for you that's fine, but please don't
belittle them just because they don't match your needs.
this up to Serverworks, not PATA), USB storage, and SATA (the SATA stack
is arranged similar to the SCSI stack with a core library that all the
drivers use, and then hardware dependent driver modules...I suspect that
since you got bit on three different hardware versions that you were in
fact hitting a core library bug, but that's just a suspicion and I could
well be wrong). What you haven't tried is any of the SCSI/SAS/FC stuff,
and generally that's what I've always used and had good things to say
about. I've only used SATA for my home systems or workstations, not any
production servers.
The USB array was never meant to be a full production system, just to
buy some time until the budget was allocated to buy a real array. Having
said that, the raid code is written to withstand the USB disks getting
disconnected as far as the driver reports it properly. Since it doesn't,
I consider it another case that shows when not to use software RAID
thinking that it will work.
As for SCSI I think it is a greatly proved and reliable technology, I've
dealt with it extensively and have always had great results. I know deal
with it mostly on non Linux based systems. But I don't think it is
affordable to most SMBs that need multi-terabyte arrays.
Actually, SCSI can fail as well. Until recently I was running servers
with multi-TB arrays, and regularly, several times a year, a drive would
fail and glitch the SCSI bus such that the next i/o to another drive
would fail. And I've had SATA drives fail cleanly on small machines, so
neither is an "always" config.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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