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Old 12-14-2010, 06:31 PM
 
Default RAID help

Ryan Wagoner wrote:
> On Tue, Dec 14, 2010 at 2:08 PM, Jason T. Slack-Moehrle
> <slackmoehrle@me.com> wrote:
<snip>
> I do know that RHEL 6 creates boot by default as larger than 100M so
> you might want to determine the size to feature proof your setup.

*sigh*
I assume that's because Fedora, at least as of 13, needs at *least* 250M,
because it dumps something ridiculous there during its preupgrade, and
then runs from it.

mark

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Old 12-14-2010, 08:08 PM
Markus Falb
 
Default RAID help

On 14.12.2010 19:49, m.roth@5-cent.us wrote:
> Hey, Jason,
>
> Jason T. Slack-Moehrle wrote:
>>
>> I have a new system with 2 Seagate 1TB SATA Enterprise level drives in it.
>>
>> I want to RAID1 (mirror) these drives.
> <snip>
>> So if I simplify, I must:
>> 1. Create a software raid partition on each drive
>> 2. Create a RAID 1 out of that partition and use a mount point of /boot
>
> Only if you want to mirror the boot partition.
>>
>> 3. Create other mount points I might want i.e swap, /home, etc
>> 4. Create RAID1 out of these partitions
>
> Only if you want each directory RAIDed. DO NOT mirror swap. Bad idea.
> <snip>

I am surprised. I always done /boot partitions as raid 1 and I always
did swap as raid 1 and therefore I would be interested about any
arguments (well better facts) against doing so.

--
Best Regards,
Markus Falb

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Old 12-14-2010, 08:18 PM
Markus Falb
 
Default RAID help

On 14.12.2010 19:37, Jason T. Slack-Moehrle wrote:
> Hi All,
>
> I have a new system with 2 Seagate 1TB SATA Enterprise level drives in it.
>
> I want to RAID1 (mirror) these drives.

...

> 1. This system support 16gb of RAM. I have 9gb in it, but I will max it out over the next few months as I find great deals on RAM, what should my SWAP space be? I recall a long while ago that SWAP should match physical RAM.

lvm, see below.

>
> 2. Any reason I can't just create a single mount point taking up the entire drive and RAID1 the entire thing? Can anyone recommend some ideal mount points and sizes?
>
> 3. What should I account for if my /var/www/html will be very large?

If you dont know in advance how your storage is allocated the best way,
use lvm. The space you dont need today is in the pool and be it
/var/www/html or swap or whatever assign it as needed in the future.

Note that its maybe better to not put /boot into lvm.

I would suggest

/dev/md0 -> /boot
/dev/md1 -> lvm with all other partitions including swap

--
Best Regards,
Markus Falb

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Old 12-14-2010, 08:36 PM
John R Pierce
 
Default RAID help

On 12/14/10 1:08 PM, Markus Falb wrote:
>> Only if you want each directory RAIDed. DO NOT mirror swap. Bad idea.
>> > <snip>
> I am surprised. I always done /boot partitions as raid 1 and I always
> did swap as raid 1 and therefore I would be interested about any
> arguments (well better facts) against doing so.

if you don't mirror swap, when any swap volume fails your system hard
crashes, negating the entire purpose of RAID.


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Old 12-14-2010, 08:49 PM
"Jason T. Slack-Moehrle"
 
Default RAID help

Hi,

> If you dont know in advance how your storage is allocated the best way,
> use lvm. The space you dont need today is in the pool and be it
> /var/www/html or swap or whatever assign it as needed in the future.
>
> Note that its maybe better to not put /boot into lvm.
>
> I would suggest
>
> /dev/md0 -> /boot
> /dev/md1 -> lvm with all other partitions including swap

OK, I have done this, I need to create mount points and I am not sure how to initially size.

How does everyone size /?

Since I know my /var/www/html will be large, say 300GB, I can create a mount point for at least that, but with LVM you are saying I can change the size later to increase it?

What other mount points should one have (besides swap)? No users will be storing sata on this box.

-Jason
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Old 12-14-2010, 08:53 PM
 
Default RAID help

Jason T. Slack-Moehrle wrote:
>
>> If you dont know in advance how your storage is allocated the best way,
>> use lvm. The space you dont need today is in the pool and be it
>> /var/www/html or swap or whatever assign it as needed in the future.
>>
>> Note that its maybe better to not put /boot into lvm.

I agree - I'd never boot /boot into lvm. If there's some problem, and I've
seen them, it may not have the lvm driver loaded, and then you're hosed.
<snip>
> OK, I have done this, I need to create mount points and I am not sure how
> to initially size.
>
> How does everyone size /?

Take a clue from the default partition layout that install wants to use.
Remember, in / will be *all* of your o/s, and third party software, and
updates.... And /var, unless that's a separate partition, with all your
logs, which can sometimes get *very* big. If you've got the space, give it
100G or 200G.
<snip>
I like /usr as a partition, and I used to like /var as one.

mark

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Old 12-14-2010, 09:16 PM
Markus Falb
 
Default RAID help

On 14.12.2010 22:49, Jason T. Slack-Moehrle wrote:
> Hi,
>
>> If you dont know in advance how your storage is allocated the best way,
>> use lvm. The space you dont need today is in the pool and be it
>> /var/www/html or swap or whatever assign it as needed in the future.
>>
>> Note that its maybe better to not put /boot into lvm.
>>
>> I would suggest
>>
>> /dev/md0 -> /boot
>> /dev/md1 -> lvm with all other partitions including swap
>
> OK, I have done this, I need to create mount points and I am not sure how to initially size.

My idea was to assign minimum at now. It could go like this:

lvm volume group -> 1000GB

for the system:
lvm logical volume for / -> 1GB
lvm logical volume for /var -> 1GB
lvm logical volume for /usr -> 1GB

lvm logical volume for /var/www/html -> 50GB

Now you have assigned 53GB out of the 1000 and the other 947GB remains
dynamically assignable from the lvm volume group.

If you need more space in one of the partitions, just grow it, out of
the pool of 947GB. Logical Volumes can be resized online and many
filesystems can be grown online (mounted) too. If the initial 1GB for
some partition proves to be to low, e.g. it has to be increased on every
server you have than adjust it to initial 2GB or whatever size is
adequat for you. I am not after numbers at all. My point is: If you dont
know how to partition, assign at minimum, allowing for future flexibility.

--
Best Regards,
Markus

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Old 12-14-2010, 09:19 PM
"Jason T. Slack-Moehrle"
 
Default RAID help

Hi Markus,

> My idea was to assign minimum at now. It could go like this:

<snip />

> If you need more space in one of the partitions, just grow it, out of
> the pool of 947GB. Logical Volumes can be resized online and many
> filesystems can be grown online (mounted) too. If the initial 1GB for
> some partition proves to be to low, e.g. it has to be increased on every
> server you have than adjust it to initial 2GB or whatever size is
> adequat for you. I am not after numbers at all. My point is: If you dont
> know how to partition, assign at minimum, allowing for future flexibility.

Perfect, makes sense now what should be done.

I appreciate the explanation.

-Jason
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Old 12-14-2010, 09:21 PM
 
Default RAID help

Markus Falb wrote:
> On 14.12.2010 22:49, Jason T. Slack-Moehrle wrote:
<snip>
>> OK, I have done this, I need to create mount points and I am not sure
>> how to initially size.
>
> My idea was to assign minimum at now. It could go like this:
>
> lvm volume group -> 1000GB
>
> for the system:
> lvm logical volume for / -> 1GB
> lvm logical volume for /var -> 1GB
> lvm logical volume for /usr -> 1GB

Sorry, but I don't think you can install with that. 10 years ago, think it
was, I was giving /, /usr and /var 4G. For most of the time since then, I
went to 20G for /usr, then 40G. And I gave /opt 20G. Giving 1G for /var is
*asking* for trouble - what happens when you have a hardware error, or an
intrusion attempt, and the logs fill the partition?

Oh, and while you're at it, install and run something like fail2ban, and
maybe clamav.
<snip>

mark

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Old 12-14-2010, 09:25 PM
Max Hetrick
 
Default RAID help

On 12/14/2010 05:21 PM, m.roth@5-cent.us wrote:

> Sorry, but I don't think you can install with that. 10 years ago, think it
> was, I was giving /, /usr and /var 4G. For most of the time since then, I
> went to 20G for /usr, then 40G. And I gave /opt 20G. Giving 1G for /var is
> *asking* for trouble - what happens when you have a hardware error, or an
> intrusion attempt, and the logs fill the partition?

I usually go one step further and split /var and /var/log on separate
partitions for the exact reason Mark mentions with logging.

Regards,
Max
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