[NBLUG/talk] RAID1 and partitions

[Omar Eljumaily]

Sorry I didn't answer the software RAID question.  Yes it is software 
RAID.  I don't like specialized hardware.  I like to use cheap, easily 
available generic hardware, which is usually better tested than more 
specialized devices.

Thanks,

Omar

On 5/2/2015 4:16 PM, Omar Eljumaily wrote:
> Thanks Mark.  Right now the machine has 4 gb of RAM, but the 
> production version will probably have 16 gb. Just one CPU with 
> probably 6 cores.  I've always wondered about swap, whether it's 
> really needed if you have enough RAM.
>
> I've noticed that Ubuntu doesn't automatically delete old system files 
> in /boot, so probably a fairly large boot partition will make things 
> easier.
>
> LVM is a big gray area for me.  If I want as swap partition without 
> having to do another RAID volume wouldn't it be necessary?  For that 
> matter could I do an ext4 /boot partition in the same volume as swap 
> and /?  Probably better to do just what is normal and use ext2, but 
> I'm just wondering.
>
> One aspect of RAID1 is the ability do a live 100% accurate mirror and 
> put the disk aside as a system configured backup.  That isn't easily 
> done with any other technology I can think of.  It involves degrading 
> a drive while it rebuilds itself, but it can be done after hours and 
> slow times.  The alternative would be a 5 hour/ terrabyte offline 
> Clonzilla backup.  Maybe there are ways to cobble that function 
> together using rsync, but it wouldn't be easy.
>
> Thanks,
>
> Omar
>
>
> On 5/1/2015 6:59 PM, Mark Street wrote:
>> Hi,
>>
>> I would go with your gut.  Putting swap on md0 just does not sound 
>> like a good thing to do.  Your experience with CentOS is similar to 
>> what I have done in the past.  Is this software RAID?  How much RAM 
>> and CPU do you have?  Depending on your answer you may not need much 
>> swap.  If any, put it at the end... or create a swap file on /
>>
>> I have been running some old mail servers for over 8 years on 
>> software raid 5 with 4 drives, only 1 drive failure the whole time.  
>> Still chugging along... it's an old Penguin Altus 1400 1U. Still 
>> kicks ass with the old Opterons and 16G of RAM.
>>
>> Keep /boot on md0 and use ext2, nothing wrong with that.  Good stable 
>> filesystem.  If you feel you need the LVM go with it or just use ext4 
>> for /, your filesystem structure seems really basic.  I have done 
>> both in hardware and in VM environments with few issues.
>>
>> Best Regards,
>>
>>
>> On 5/1/2015 10:23 AM, Omar Eljumaily wrote:
>>> Does anybody have any tips for setting up a RAID1 array on Ubuntu?
>>>
>>> I've looked at this:
>>>
>>> https://help.ubuntu.com/lts/serverguide/advanced-installation.html
>>>
>>> It suggests setting up
>>>
>>> md0 as a swap partition and
>>> md1 as an ext4 / partition which is also bootable.
>>>
>>> My experience with Centos is to do:
>>>
>>> md0: /boot with ext2
>>>
>>> md1: as an LVM volume creating partitions:
>>>
>>> swap
>>> and / as ext4
>>>
>>> My goal is reliability and to be able to boot into either volume 
>>> when the other is degraded.  Is there any standard way to do this?
>>>
>>> Thanks,
>>>
>>> Omar
>>>
>>>
>>>
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>>
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