That helps a lot - thank you.
I wish I knew it before... Information Roch put on his blog should be
explained both in MAN pages and ZFS Admin Guide - as this is something
one would not expect.
It actually means raid-z is useless in many enviroments compare to
traditional raid-5.
Well,
Jeff Bonwick wrote:
...
Since we know that intent log blocks don't live for more than a
single transaction group (which is about five seconds), there's
no reason to allocate them space-efficiently. It would be far
better, when allocating a B-byte intent log block in an N-disk
RAID-Z group, to
Robert Milkowski writes:
btw: just a quick thought - why not to write one block only on 2 disks
(+checksum on a one disk) instead of spreading one fs block to N-1
disks? That way zfs could read many fs block at the same time in case
of larger raid-z pools. ?
That's what you
On Thu, 2006-06-01 at 04:36, Jeff Bonwick wrote:
It would be far
better, when allocating a B-byte intent log block in an N-disk
RAID-Z group, to allocate B*N bytes but only write to one disk
(or two if you want to be paranoid). This simple change should
make synchronous I/O on N-way RAID-Z
We'll be much better able to help you reach your performance goals
if you can state them as performance goals.
In particular, knowing the latency requirements is important.
Uncompressed HD video runs at 1.5 Gbps; two streams would require 3 Gbps, or
375 MB/sec. The requirement for real-time
What about small random writes? Won't those also require reading from all disks
in RAID-Z to read the blocks for update, where in mirroring only one disk need
be accessed? Or am I missing something?
(It seems like RAID-Z is similar to RAID-3 in its performance characteristics,
since both
I have some questions about modify filesystem block.
When we want to modify existing block ZFS makes new one and destroy old. OK -
it is copy-on-write
mechanism. But if we want to modify only a part of the block what does it work?
What does ZFS do with rest of the block? Whether size of it is
Jeff Bonwick wrote:
http://blogs.sun.com/roller/page/roch?entry=when_to_and_not_to
thanks, that is very useful information. it pretty much rules out raid-z
for this workload with any reasonable configuration I can dream up
with only 12 disks available. it looks like mirroring is
Just as a hypothetical (not looking for exact science here folks..), how would
ZFS fare (in your educated opinion) in this sitation:
1 - Machine with 8 10k rpm SATA drives. High performance machine of sorts (ie
dual proc, etc..let's weed out cpu/memory/bus bandwidth as much as possible
from
On Thu, Jun 01, 2006 at 02:46:32PM +0200, Robert Milkowski wrote:
btw: what differences there'll be between raidz1 and raidz2? I guess
two checksums will be stored so one loose approximately space of two
disks in a one raidz2 group. Any other things?
The difference between raidz1 and raidz2 is
Hello David,
Thursday, June 1, 2006, 11:35:41 PM, you wrote:
DJO Just as a hypothetical (not looking for exact science here
DJO folks..), how would ZFS fare (in your educated opinion) in this sitation:
DJO 1 - Machine with 8 10k rpm SATA drives. High performance machine
DJO of sorts (ie dual
On Thu, Jun 01, 2006 at 11:35:41AM -1000, David J. Orman wrote:
3 - App server would be running in one zone, with a (NFS) mounted ZFS
filesystem as storage.
4 - DB server (PgSQL) would be running in another zone, with a (NFS)
mounted ZFS filesystem as storage.
Why would you use NFS? These
Hello David,
Friday, June 2, 2006, 12:52:05 AM, you wrote:
DJO - Original Message -
DJO From: Matthew Ahrens [EMAIL PROTECTED]
DJO Date: Thursday, June 1, 2006 12:30 pm
DJO Subject: Re: [zfs-discuss] question about ZFS performance for
webserving/java
There is no need for multiple
- Original Message -
From: Robert Milkowski [EMAIL PROTECTED]
Date: Thursday, June 1, 2006 1:17 pm
Subject: Re[2]: [zfs-discuss] question about ZFS performance for webserving/java
Hello David,
The system itself won't take too much space.
You can create one large slice form the rest
Please add to the list the differences on locally or remotely attach
vdevs: FC, SCSI/SATA, or iSCSI. This is the part that is troubling me
most, as there are wildly different performance characteristics when
you use NFS with any of these backends with the various configs of
ZFS. Another thing is
On Thu, Jun 01, 2006 at 06:40:15PM -0500, Tao Chen wrote:
ABR What about small random writes? Won't those also require reading
ABR from all disks in RAID-Z to read the blocks for update, where in
ABR mirroring only one disk need be accessed? Or am I missing something?
If I understand it
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