The risk to using swap on raid is that resync and swap operations can
not go on at the same time so that if the swap raid set has been
damaged and is resyncing, swap can not be allowed. There are several
workaround scripts that detect the resync and allow it to finish
before proceeding. Would
RAID-5 for swap or buy
RAM?
Linux uses swap intelligently, if areas of memory don't change they get
swapped out to disk, making more physical RAM available for file caching,
etc. Having swap is good even if you have oodles of RAM just for that
reason.
Bill Carlson
Systems Programmer
Does anybody really want to wait while their swap data is duplicated
out to multiple disks by a CPU that is working to free up memory to
run applications?
Isn't Swapping slow enough already?
Why not simply swap on multiple disks, get Hardware RAID-5 for swap
or buy RAM?
If ANY swap
Does anybody really want to wait while their swap data is duplicated out to
multiple disks by a CPU that is working to free up memory to run
applications?
Isn't Swapping slow enough already?
Why not simply swap on multiple disks, get Hardware RAID-5 for swap or buy
RAM?
Well, the reason we have our systems set to swap on RAID (we use RAID-1) is
that this improves our robustness. Even if one of our disks dies then the
swap continues to work and the system is still stable. Also, I believe, it
is possible to use a RAID-10 to stripe and mirror and actually improve
Is swapping on Hardware RAID safer than software RAID?
Matthew Clark.
On Sun, Mar 12, 2000 at 02:46:36PM -, Matthew Clark wrote:
Is swapping on Hardware RAID safer than software RAID?
Matthew Clark.
yes, hardware raid should appear as a normal disk to linux
L.
--
Luca Berra -- [EMAIL PROTECTED]
Communication Media Services S.r.l.
In an extreme case, a drive could fail and a new one hot added while the
machine is live. Then reconstruction could occur while the swap area is
active. You might also like a cron job if you _REALLY_ want?
On Tue, 1 Feb 2000, Holger Kiehl wrote:
-Hello
-
-Since swapping on a software raid is
On Tue, Jan 04, 2000 at 05:35:19PM -0800, Michael wrote:
Could the Raid experts revisit a portion of the discussion about swap
on raid. I understand that the use/non-use of buffer space during
reconsturction vs swap creates a problem for swap on raid, however in
my pea-sized brain
Could the Raid experts revisit a portion of the discussion about swap
on raid. I understand that the use/non-use of buffer space during
reconsturction vs swap creates a problem for swap on raid, however in
my pea-sized brain it appears that this would be a problem only if a
full partition
On Wed, 14 Jul 1999, Roeland M.J. Meyer wrote:
I think that he's talking about RAID10. Take two RAID1 devices and bond
them with RAID0.
no i think he means two seperate raid1 md devices for swap. raid10
would be even more overhead imo - but if anyone has empirical
evidence i'd love to see
Paul Jakma [EMAIL PROTECTED] writes:
well, i'm just testing at the moment to see if it's feasible. Anyway,
i never mentioned an amount of swap, i didn't say anything about
384mb. I actually have 4 partitions of 40MB = 160MB total. After
RAID5 - 120MB, which is reasonable.
Funny, you should
I don't think the 128Meg swap limit applies any more!
On 15 Jul 1999, Osma Ahvenlampi wrote:
Paul Jakma [EMAIL PROTECTED] writes:
well, i'm just testing at the moment to see if it's feasible. Anyway,
i never mentioned an amount of swap, i didn't say anything about
384mb. I actually
After reading this thread on swap and RAID, I have the following remarks:
1. With kernel 2.2.x you can use swap partitions larger than 128MB (this
was actually true starting with the 2.1.x developemtn kernels)
2. The kernel automatically stripes across equal priority swap spaces.
(from
Marc Mutz wrote:
MadHat wrote:
A James Lewis wrote:
I don't think the 128Meg swap limit applies any more!
I think it is possible to create swap 'spaces' larger than 128M, but it
will only take advantage of the first 128M (but I can't find an exact
answer in the kernel
I think it is possible to create swap 'spaces' larger than 128M, but it
will only take advantage of the first 128M (but I can't find an exact
answer in the kernel right now). Can you point me to a page or kernel
source that says you can use more that 128M, I can't find it. Thanks.
You may
Helge Hafting wrote:
I think it is possible to create swap 'spaces' larger than 128M, but it
will only take advantage of the first 128M (but I can't find an exact
answer in the kernel right now). Can you point me to a page or kernel
source that says you can use more that 128M, I can't
Paul Jakma [EMAIL PROTECTED] writes:
with RAID1 i have 1/2 the physical space available for swap.
with RAID5 i have 3/4 of physical space available for swap.
hence i choose RAID5.
seems a lot more efficient to me.
Space-efficient, yes, speed-efficient, certainly not. Are you
absolutely
[mailto:[EMAIL PROTECTED]]On Behalf Of
Jonathan F. Dill
Sent: Tuesday, July 13, 1999 5:20 PM
AFAIK unless you've done something to the kernel to get around that
limit. What's the point of running swap on RAID anyway? Memory is
cheap these days--seems to me rather than wasting time
[mailto:[EMAIL PROTECTED]]On Behalf Of Paul Jakma
Sent: Wednesday, July 14, 1999 10:01 AM
To: Osma Ahvenlampi
On 14 Jul 1999, Osma Ahvenlampi wrote:
Paul Jakma [EMAIL PROTECTED] writes:
with RAID1 i have 1/2 the physical space available for swap.
with RAID5 i have 3/4 of physical
Roeland M.J. Meyer wrote:
snip
RAID-1 is faster? since when? RAID-5 should be faster at reads. I get
~25MB/s sustained read across 4 U/W disks, 16MB/s sustained write
according to bonnie. (i've never tried RAID-1 to be honest).
I think that he's talking about RAID10. Take two RAID1
rebooting.
Much thanks to developers, A James Lewis, and Bruno Prior.
Now, I would like to raid-1 my swap partition for high-availability. I
read in the Software-Raid-HOWTO that as of 2.0.x that it wasn't supported
and would cause crashes. Is that still the case with the 2.2.5-22 kernel
.
Now, I would like to raid-1 my swap partition for high-availability. I
read in the Software-Raid-HOWTO that as of 2.0.x that it wasn't supported
and would cause crashes. Is that still the case with the 2.2.5-22 kernel?
If it will work, is there a HOWTO, Recipe, etc. that describes the process
On Mon, 12 Jul 1999, Joel Fowler wrote:
Now, I would like to raid-1 my swap partition for high-availability. I
read in the Software-Raid-HOWTO that as of 2.0.x that it wasn't supported
and would cause crashes. Is that still the case with the 2.2.5-22 kernel?
If it will work
On Mon, 12 Jul 1999, Paul Jakma wrote:
On Mon, 12 Jul 1999, Joel Fowler wrote:
Now, I would like to raid-1 my swap partition for high-availability. I
read in the Software-Raid-HOWTO that as of 2.0.x that it wasn't supported
and would cause crashes. Is that still the case
On Mon, 12 Jul 1999 [EMAIL PROTECTED] wrote:
The HOWTO states that swapping on RAID is unsafe, and that is probably
unjustified with the latest RAID patches.
yes swapping is safe. It's _slightly_ justified with RAID1 to be fair -
but i've tried it myself and was unable to reproduce anything
Why does anybody want to use swap-on-RAID with any RAID level than 1?
Wouldn't it be much faster if you used multiple swap spaces?
Marc
--
Marc Mutz [EMAIL PROTECTED]http://marc.mutz.com/
University of Bielefeld, Dep. of Mathematics / Dep. of Physics
PGP-keyID's
On Tue, 13 Jul 1999, Marc Mutz wrote:
Why does anybody want to use swap-on-RAID with any RAID level than 1?
Wouldn't it be much faster if you used multiple swap spaces?
Marc
cause i have 4 partitions dedicated to swap. with raid-1 i have only
1/5 the space available to use for swap
On Tue, 13 Jul 1999, Paul Jakma wrote:
On Tue, 13 Jul 1999, Marc Mutz wrote:
Why does anybody want to use swap-on-RAID with any RAID level than 1?
Wouldn't it be much faster if you used multiple swap spaces?
Marc
cause i have 4 partitions dedicated to swap. with raid
On Tue, 13 Jul 1999, Marc Mutz wrote:
Why does anybody want to use swap-on-RAID with any RAID level
than 1? Wouldn't it be much faster if you used multiple swap
spaces?
Pretty simple. If your swap space becomes corrupted or you lose the
disk it resides on, the kernel
Paul Jakma wrote:
On Tue, 13 Jul 1999, Marc Mutz wrote:
Why does anybody want to use swap-on-RAID with any RAID level than 1?
Wouldn't it be much faster if you used multiple swap spaces?
Marc
cause i have 4 partitions dedicated to swap. with raid-1 i have only
1/5 the space
. Not sure what to, maybe 2GB.
What's the point of running swap on RAID anyway?
what happens if the disk with your swap on it suddenly dies? your
machine dies too. with linux-raid it shouldn't.*
* but linux scsi isn't particularly robust though.
--
Paul Jakma
[EMAIL PROTECTED] http
: [EMAIL PROTECTED]
Betreff: Re: Swap on raid
Empfänger: Dietmar Stein
Kopie-Empfänger: [EMAIL PROTECTED] , [EMAIL PROTECTED]
Datum: 12. Mai 1999 01:13
Do other people have opinions on the "Lifetime" MTBF of a harddrive... My
experience is about 15000 hours continuous
Do other people have opinions on the "Lifetime" MTBF of a harddrive... My
experience is about 15000 hours continuous operation.
I've seen manufacturers claim 30 hours MTBF, but that's not realistic
in my experience... mabe 3 in a more controlled environment with good
aircon etc
On Mon, May 10, 1999 at 07:26:53PM +0200, Dietmar Stein wrote:
Hi
At work we got much HP-Workstations and -Servers; everyone got a
swap-partition which is of same size as physical memory (or even
bigger).
hp-ux uses swap partitions as a dump device, something i'd love
to see on linux
Hi
Ok - I understand what you are meaning; I think we have just different
opinions towards lifetime of a harddrive.
Maybe, I will go on using only one disk for swap - but it is interesting
seeing other opinions concerning lifetime of a hdd and security.
Greetings, Dietmar
Luca Berra wrote:
Hi,
You can run a system without a swap device. But if you do 'swapoff -a'
_after_ a swap device failure, you are dead (if swap had any virtual
data stored in it.)
'swapoff -a' copies virtual data stored in the swap device to physical
memory before closing the device. This is much different
PROTECTED]; [EMAIL PROTECTED]
Sent: Sunday, May 09, 1999 06:39
Subject: Re: Swap on raid
Hi,
Having read Jabob's Software-RAID HOWTO (0.90.2 - alpha 27th of
February 1997), I learned that you are not supposed to swap on a raid
partition. You can make the kernel stripe swap on different devices
On Sun, 9 May 1999, Gulcu Ceki wrote:
On the other hand, if the intent is higher reliability, then one can
swap on a RAID-1 partition.
i wonder, can you have your swap on a raid5 partition? raid-1 seems
a bit of a waste of hdd space.
--
Paul Jakma
[EMAIL PROTECTED] http
Hi
A question in between: what sense does it make to have the swap onto
raid?
I think, that moment your machine starts swapping you´ll get some
performance problems which wouldn't be solved by using "raid-swap"
instead of swap on a single disk or whatever. Think of the meani
On Sun, 9 May 1999, Dietmar Stein wrote:
A question in between: what sense does it make to have the swap onto
raid?
If the swap partition becomes inaccessible, the machine crashes. that
means if a disk goes down with a swap partition on it, you are dead.
If the partition is on "
on a non-redundant system.
Steve
- Original Message -
From: Dietmar Stein [EMAIL PROTECTED]
To: Paul Jakma [EMAIL PROTECTED]; [EMAIL PROTECTED]
Sent: Sunday, May 09, 1999 12:30
Subject: Re: Swap on raid
Hi
A question in between: what sense does it make to have the swap onto
raid?
I
On Sun, 9 May 1999, Dietmar Stein wrote:
Hi
A question in between: what sense does it make to have the swap onto
raid?
I think, that moment your machine starts swapping you´ll get some
performance problems which wouldn't be solved by using "raid-swap"
inste
- Ursprüngliche Nachricht -
Absender: [EMAIL PROTECTED]
Betreff: Re: Swap on raid
Empfänger: Dietmar Stein
Kopie-Empfänger: [EMAIL PROTECTED]
Datum: 09. Mai 1999 21:09
On Sun, 9 May 1999, Dietmar Stein wrote:
Hi
A question in between: what sense does it make to have the swap onto
raid
Paul Jakma [EMAIL PROTECTED] writes:
We know raid1 works, but would swap on raid5? i hope it would, as
raid5 is less wasteful of disk space than raid1.
But the couple of hundred megs you need for swap (at maximum) don't
really amount to anything in a big system. raid1 is faster than
raid5.
--
work on a partition or a file, cause at swapon time, the
blocks are mapped for direct access.
swap running on raid then, if it works at all, is not actually protecting you.
the swap code in the kern is capable of doing striping automatically if you
have two swap partitions.
i may be completely
swap running on raid then, if it works at all, is not actually
protecting you. the swap code in the kern is capable of doing
striping automatically if you have two swap partitions.
Yes it does. If one of two swap partitions goes down on non-raid
drives, the kernel locks up and you loose
Hi again,
I have done a small test with a raid-1 swap partition. I have filled up
memory so that the system swaps
to the raid swap partition with a little test program and the system
worked, top shows 800M of swap used
and still going. Does this tell me that it will always work
Helge Hafting wrote:
Why do you want to swap onto raid?
Creating ordinary swap partitions with equal priority on
several drives will achieve the same speedup as far as I know,
as the kernel will spread swapping across all the swap partitions.
This achieves the same speedup as raid-0
block device IO routines.
this is how swap can work on a partition or a file, cause at swapon
time, the blocks are mapped for direct access.
No, for files, we do the mapping on demand, not all at once on swapon.
swap running on raid then, if it works at all, is not actually
protecting you
Hi,
On Wed, 14 Apr 1999 15:32:40 -0400, "Joe Garcia" [EMAIL PROTECTED] said:
Swapping to a file should work, but if I remember correctly you get
horrible performance.
Swap-file performance on 2.2 kernels is _much_ better.
--Stephen
Hi,
On Wed, 14 Apr 1999 21:59:49 +0100 (BST), A James Lewis [EMAIL PROTECTED]
said:
It wasn't a month ago that this was not possible because it needed to
allocate memory for the raid and couldn't because it needed to swap to
do it? Was I imagining this or have you guys been working too
Stephen C. Tweedie wrote:
Hi,
On Wed, 14 Apr 1999 21:59:49 +0100 (BST), A James Lewis
[EMAIL PROTECTED]
said:
It wasn't a month ago that this was not possible because it needed
to
allocate memory for the raid and couldn't because it needed to swap
to
do it? Was I imagining this or
Hi folks,
we are trying to set up a mirrored (raid-1) system for reliability
but it is not possible according
to the latest HOWTO to swap onto a raid volume. Is there any change on
this?
Has anyone set up a system like this with/without swap configured and
what is your experience?
We have
On Wed, 14 Apr 1999 [EMAIL PROTECTED] wrote:
Hi folks,
we are trying to set up a mirrored (raid-1) system for reliability
but it is not possible according
to the latest HOWTO to swap onto a raid volume. Is there any change on
this?
it does work for me (i do not actually use
Ingo Molnar [EMAIL PROTECTED] writes:
it does work for me (i do not actually use it as such, but i've done some
stresstesting under heavy load). Let me know if you find any problems.
Hmm? Since when does swapping work on raid-1? How about raid-5?
--
Osma Ahvenlampi
On 14 Apr 1999, Osma Ahvenlampi wrote:
Ingo Molnar [EMAIL PROTECTED] writes:
it does work for me (i do not actually use it as such, but i've done some
stresstesting under heavy load). Let me know if you find any problems.
Hmm? Since when does swapping work on raid-1? How about raid-5?
Hello All, Cool now when do we get the new alpha-lilo
alpha-silo, alpha-milo tools to support the alpha-raid ?
I know, I know, 'hack away...' tnx, JimL
On Wed, 14 Apr 1999, Ingo Molnar wrote:
On 14 Apr 1999, Osma Ahvenlampi wrote:
Ingo Molnar [EMAIL PROTECTED]
Swapping to a file should work, but if I remember correctly you get horrible
performance.
Joe
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of [EMAIL PROTECTED]
Sent: Wednesday, April 14, 1999 9:36 AM
To: Linux Raid
Subject: Swap on raid
Hi
Errr?
It wasn't a month ago that this was not possible because it needed to
allocate memory for the raid and couldn't because it needed to swap to do
it? Was I imagining this or have you guys been working too hard!
Either way, brill!
James
On Wed, 14 Apr 1999, Ingo Molnar wrote:
On 14
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