On Sat, 23 Feb 2008 21:40:08 +0100, Nagilum
[EMAIL PROTECTED] said:
[ ... ]
* Doing unaligned writes on a 13+1 or 12+2 is catastrophically
slow because of the RMW cycle. This is of course independent
of how one got to the something like 13+1 or a 12+2.
nagilum Changing a single byte in a
[ ... ]
* Suppose you have a 2+1 array which is full. Now you add a
disk and that means that almost all free space is on a single
disk. The MD subsystem has two options as to where to add
that lump of space, consider why neither is very pleasant.
No, only one, at the end of the md device
On Tue, 19 Feb 2008 14:25:28 -0500, Norman Elton
[EMAIL PROTECTED] said:
[ ... ]
normelton The box presents 48 drives, split across 6 SATA
normelton controllers. So disks sda-sdh are on one controller,
normelton etc. In our configuration, I run a RAID5 MD array for
normelton each controller,
This might be related to raid chunk positioning with respect
to LVM chunk positioning. If they interfere there indeed may
be some performance drop. Best to make sure that those chunks
are aligned together.
Interesting. I'm seeing a 20% performance drop too, with default
RAID and LVM chunk
What sort of tools are you using to get these benchmarks, and can I
used them for ext3?
The only simple tools that I found that gives semi-reasonable
numbers avoiding most of the many pitfalls of storage speed
testing (almost all storage benchmarks I see are largely
meaningless) are recent
On Sun, 17 Feb 2008 07:45:26 -0700, Conway S. Smith
[EMAIL PROTECTED] said:
[ ... ]
beolach Which part isn't wise? Starting w/ a few drives w/ the
beolach intention of growing; or ending w/ a large array (IOW,
beolach are 14 drives more than I should put in 1 array expect
beolach to be safe
On Sat, 16 Feb 2008 20:58:07 -0700, Beolach
[EMAIL PROTECTED] said:
beolach [ ... ] start w/ 3 drives in RAID5, and add drives as I
beolach run low on free space, eventually to a total of 14
beolach drives (the max the case can fit).
Like for for so many other posts to this list, all that is
On Sun, 27 Jan 2008 20:33:45 +0100, Keld Jørn Simonsen
[EMAIL PROTECTED] said:
keld Hi I have tried to make a striping raid out of my new 4 x
keld 1 TB SATA-2 disks. I tried raid10,f2 in several ways:
keld 1: md0 = raid10,f2 of sda1+sdb1, md1= raid10,f2 of sdc1+sdd1, md2 = raid0
keldof
Why does mdadm still use 64k for the default chunk size?
Probably because this is the best balance for average file
sizes, which are smaller than you seem to be testing with?
Well average file sizes relate less to chunk sizes than access
patterns do. Single threaded sequential reads with
On Sun, 23 Dec 2007 08:26:55 -0600, Jon Nelson
[EMAIL PROTECTED] said:
I've found in some tests that raid10,f2 gives me the best I/O
of any raid5 or raid10 format.
Mostly, depending on type of workload. Anyhow in general most
forms of RAID10 are cool, and handle disk losses better and so
on.
On Tue, 25 Dec 2007 19:08:15 +,
[EMAIL PROTECTED] (Peter Grandi) said:
[ ... ]
It's the raid10,f2 *read* performance in degraded mode that is
strange - I get almost exactly 50% of the non-degraded mode
read performance. Why is that?
[ ... ] the mirror blocks have to be read from
[ ... on RAID1, ... RAID6 error recovery ... ]
tn The use case for the proposed 'repair' would be occasional,
tn low-frequency corruption, for which many sources can be
tn imagined:
tn Any piece of hardware has a certain failure rate, which may
tn depend on things like age, temperature,
On Thu, 22 Nov 2007 22:09:27 -0500, [EMAIL PROTECTED]
said:
[ ... ] a RAID 10 personality defined in md that can be
implemented using mdadm. If so, is it available in 2.6.20.11,
[ ... ]
Very good choice about 'raid10' in general. For a single layer
just use '-l raid10'. Run 'man mdadm', the
On Mon, 22 Oct 2007 15:33:09 -0400 (EDT), Justin Piszcz
[EMAIL PROTECTED] said:
[ ... speed difference between PCI and PCIe RAID HAs ... ]
I recently built a 3 drive RAID5 using the onboard SATA
controllers on an MCP55 based board and get around 115MB/s
write and 141MB/s read. A fourth
On Thu, 18 Oct 2007 16:45:20 -0700 (PDT), nefilim
[EMAIL PROTECTED] said:
[ ... ]
3 x 500GB WD RE2 hard drives
AMD Athlon XP 2400 (2.0Ghz), 1GB RAM
[ ... ]
avg-cpu: %user %nice %system %iowait %steal %idle
1.010.00 55.56 40.400.003.03
[ ... ]
which is
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