Bill Davidsen wrote:
Gordon Messmer wrote:
...
No. Even in the worst case it would read N-2 blocks (you are writing a
new data block and calculating new parity), and two writes.
Let's just say that I've seen controllers behave in ways that I don't
understand, and that I agree, the cost
Gordon Messmer wrote:
Bill Davidsen wrote:
Gordon Messmer wrote:
Your assertion ignores the fact that filesystems themselves are, in
fact, databases. Real-world experience with many production systems
and many workloads has convinced me to use RAID 5 as rarely as
possible. Even when I'm
Gordon Messmer wrote:
Philip A. Prindeville wrote:
If you're *not* a database weenie, and you're doing usual manly things
with your filesystem (like lots of compiles, for instance), you're
typically not going to be modifying files in place at all.
That's not quite it. RAID 5 performance
Gordon Messmer wrote:
Chris Tyler wrote:
On Tue, 2008-12-30 at 01:02 -0800, Gordon Messmer wrote:
That's not quite it. RAID 5 performance suffers because every write
requires that the entire block that's being written be read from
every drive in the array, parity calculated, and then the
Bill Davidsen wrote:
Gordon Messmer wrote:
Your assertion ignores the fact that filesystems themselves are, in
fact, databases. Real-world experience with many production systems
and many workloads has convinced me to use RAID 5 as rarely as
possible. Even when I'm forced to use it, I
Chris Tyler wrote:
On Tue, 2008-12-30 at 01:02 -0800, Gordon Messmer wrote:
That's not quite it. RAID 5 performance suffers because every write
requires that the entire block that's being written be read from every
drive in the array, parity calculated, and then the data and parity
written
Philip A. Prindeville wrote:
If you're *not* a database weenie, and you're doing usual manly things
with your filesystem (like lots of compiles, for instance), you're
typically not going to be modifying files in place at all.
That's not quite it. RAID 5 performance suffers because every
On Tue, 2008-12-30 at 01:02 -0800, Gordon Messmer wrote:
Philip A. Prindeville wrote:
If you're *not* a database weenie, and you're doing usual manly things
with your filesystem (like lots of compiles, for instance), you're
typically not going to be modifying files in place at all.
Philip A. Prindeville wrote:
I was going back over the archives and saw a lot of people complaining
about how slow RAID5 was, and did some quick research into this.
Yes, it's true that it can be slowed down if you're rewriting
fragmentary data in place, since this takes a read-modify-write
I was going back over the archives and saw a lot of people complaining
about how slow RAID5 was, and did some quick research into this.
Yes, it's true that it can be slowed down if you're rewriting
fragmentary data in place, since this takes a read-modify-write operation.
But that's true of
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