Backup of RAID1 partition
Hi all, I have two discs in RAID1 with three partitions on it: hda1(c) - swap hda2(c) - / hda3(c) - /job I will do some experiment with OS, so I should backup / partition (10GB). I have tape device that I big enough for backup of / partition purpose, but what will be the best way to do so? I need backup for bare metal recovery of / partition. dd, star...? Can somebody help me with backup/restore method here? Zoran
On Tuesday 22 August 2006 22:54, Zoran Ljubisic wrote:
Hi all,
I have two discs in RAID1 with three partitions on it:
hda1(c) - swap
hda2(c) - /
hda3(c) - /job
Why are you running swap on a raid device?
I will do some experiment with OS, so I should backup / partition (10GB). I have tape device that I big enough for backup of / partition purpose, but what will be the best way to do so?
I need backup for bare metal recovery of / partition.
No tape software backup will be suitable for bare metal backup/restore. There is no OS in a bare metal situation, so you have no way to restore. Further, taking backups that are capable of being restored to a new raw disk usually entails taking the disk off line long enough to do it. You have to essentially do a partition dump, and you usually can't do that on a running partition. Personally I never plan on doing bare metal retorations. I back up data and other critical configurations (such as email setups, etc) and plan on restoring the data to a freshly installed OS on the new box if that becomes necessary. -- _____________________________________ John Andersen
On Wed, 23 Aug 2006, John Andersen wrote:
On Tuesday 22 August 2006 22:54, Zoran Ljubisic wrote:
Hi all,
I have two discs in RAID1 with three partitions on it:
hda1(c) - swap
hda2(c) - /
hda3(c) - /job
Why are you running swap on a raid device?
I will do some experiment with OS, so I should backup / partition (10GB). I have tape device that I big enough for backup of / partition purpose, but what will be the best way to do so?
I need backup for bare metal recovery of / partition.
No tape software backup will be suitable for bare metal backup/restore. There is no OS in a bare metal situation, so you have no way to restore.
Further, taking backups that are capable of being restored to a new raw disk usually entails taking the disk off line long enough to do it. You have to essentially do a partition dump, and you usually can't do that on a running partition.
Personally I never plan on doing bare metal retorations. I back up data and other critical configurations (such as email setups, etc) and plan on restoring the data to a freshly installed OS on the new box if that becomes necessary.
-- _____________________________________ John Andersen
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
On Wednesday 23 August 2006 00:41, Justin Piszcz wrote:
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
Most systems don't use swap. Servers probably never should. Most recommendations I've read are NOT to use raid for swap. Some processes might die, but usually the system survives when swap is demounted. -- _____________________________________ John Andersen
On Wednesday 23 August 2006 00:46, John Andersen wrote:
On Wednesday 23 August 2006 00:41, Justin Piszcz wrote:
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
Most systems don't use swap. Servers probably never should.
Most recommendations I've read are NOT to use raid for swap.
Some processes might die, but usually the system survives when swap is demounted.
More info: From http://www.tldp.org/HOWTO/Software-RAID-HOWTO-2.html 2.3 Swapping on RAID There's no reason to use RAID for swap performance reasons. The kernel itself can stripe swapping on several devices, if you just give them the same priority in the /etc/fstab file. -- _____________________________________ John Andersen
On Wed, 23 Aug 2006, John Andersen wrote:
On Wednesday 23 August 2006 00:46, John Andersen wrote:
On Wednesday 23 August 2006 00:41, Justin Piszcz wrote:
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
Most systems don't use swap. Servers probably never should.
Most recommendations I've read are NOT to use raid for swap.
Some processes might die, but usually the system survives when swap is demounted.
More info: From http://www.tldp.org/HOWTO/Software-RAID-HOWTO-2.html
2.3 Swapping on RAID There's no reason to use RAID for swap performance reasons. The kernel itself can stripe swapping on several devices, if you just give them the same priority in the /etc/fstab file. -- _____________________________________ John Andersen
Yeah, that is the 'cheap' way to do it if you don't want to go through the hassle of setting up your box to use SW RAID. Justin.
On Wed, 23 Aug 2006, John Andersen wrote:
On Wednesday 23 August 2006 00:41, Justin Piszcz wrote:
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
Most systems don't use swap. Servers probably never should.
Most recommendations I've read are NOT to use raid for swap.
Some processes might die, but usually the system survives when swap is demounted.
-- _____________________________________ John Andersen
You sure about that? Even if you have 64GB of RAM, the kernel developers say you should still use swap when I asked them about it.
You sure about that? Even if you have 64GB of RAM, the kernel developers say you should still use swap when I asked them about it.
Yes because for some strange reason, the OOM killer kicks in sometimes. And if it is just 32 MB swap you add to the 64 GB RAM system. It's not much that you need. Jan Engelhardt --
On Wednesday 23 August 2006 00:49, Justin Piszcz wrote:
On Wed, 23 Aug 2006, John Andersen wrote:
On Wednesday 23 August 2006 00:41, Justin Piszcz wrote:
Why are you running swap on a raid device?
You DEFINITELY want to do this, otherwise, when 1 disk dies, so does your system if its using that swap!
Most systems don't use swap. Servers probably never should.
Most recommendations I've read are NOT to use raid for swap.
Some processes might die, but usually the system survives when swap is demounted.
-- _____________________________________ John Andersen
You sure about that? Even if you have 64GB of RAM, the kernel developers say you should still use swap when I asked them about it.
Swap is like the pistol you keep under your pillow. Best if never needed. Nice to have in an emergency, but it will not protect you from all disasters. John's Razor: Anything that contrives to memory starve a properly provisioned server will also exhaust swap. ;-) -- _____________________________________ John Andersen
participants (4)
-
Jan Engelhardt -
John Andersen -
Justin Piszcz -
Zoran Ljubisic