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SP Storage Partitioning


Andy
18-08-2009, 12:11
Bare in mind 1TB of it is stuff from my website, and 1.7TB is movies/tv series, and the rest are my documents, music and backups.

freshwire
18-08-2009, 12:02
Yes because you keep things? I delete em once I'm done.

Andy
18-08-2009, 11:12
LOL I use 3.5TB Big difference.

freshwire
18-08-2009, 11:00
I changed over to raid 0 a few months back cus 'people' were saying I didn't have much disk space. But I use like 30-40GB so I don't need a lot :P

Andy
18-08-2009, 10:56
Ah that could be why its not mentioned if not all controllers support it. I use RAID0 myself for 160MB/s read/write.

freshwire
18-08-2009, 10:48
http://en.wikipedia.org/wiki/Standar..._1_performance

I have also used raid 1 myself in the past and achieved 150MB/s read speed on drives that don't go over 80MB/s on their own.

It can however depend on the data access pattern. How the data is spread over the drives and whether or not the data is accessed randomly.

Also some raid controllers don't support this completely.

Andy
18-08-2009, 10:43
Everywhere I have read said the read and write performance was untouched. You got a link to your source for that?

freshwire
18-08-2009, 10:41
For raid 1 the read performance: "can go up roughly as a linear multiple of the number of copies".

Andy
18-08-2009, 10:37
RAID0 = Striping. Adds all the drives together. No redundancy. Offers much greater read/write speeds. E.G. 3x1TB drives in RAID0 gives 3TB total space.

RAID1 = Mirroring. Duplicates the contents of one drive to another exactly for redundancy. Does not affect read/write speeds. EG. 2x1TB drives in RAID0 gives 1TB total space.

RAID5 = Striping with parity. Adds all the drives together minus one drive (n-1) for parity. Offers the ability for any single disk failure and still allow recovery. Offers much greater read/write speeds. E.G. 5x1TB drives gives 4TB total space.

RAID6 = Striping with double parity. Adds all the drives together minus two drives (n-2) for parity. Offers the ability for any two disks to fail and still allow recovery. Offers much greater read/write speeds. E.G. 5x1TB drives gives 3TB total space.

RAID1+0 = Striping and mirroring. Adds two sets of n/2 drives together in striping, then one striped set becomes a mirror for redundancy. Offers much greater read/write speeds. E.G. 4x1TB drives gives 2TB total space.

derchris
18-08-2009, 10:23
Yeah, think I was too tired when I tried to set it up
But all working fine since last night.

freshwire
18-08-2009, 09:19
Raid 5/6 I was going to say that! I'm suprised I even knew that. Yes in all case raid 1 combines all drives each being a backup and each providing a bit more read speed. Raid 5/6 is combining the principals of raid 0 and raid 1.

tim2718281
18-08-2009, 06:20
Quote Originally Posted by derchris
Even with Raid 1, I should have 3 TB available.
So I selected Raid Partitioning, and was presented with only 1.5 TB.
RAID 1 is a way to use two physical disks.

I expect what you need is either two RAID-1 sets of 1.5TB each, or a single RAID-10 of 3GB, or maybe RAID 5 of 4.5GB, or RAID 6 of 3GB.

gigabit
18-08-2009, 01:03


Anyway, I'm waiting for my new SP storage, hope the manager is fixed by the time i get it...

derchris
18-08-2009, 00:43
Doh,

someone said yesterday you should better go to sleep before you do any stupid stuff.
Almost the same for my case.
What I actually tried the whole time is not possible at all.
Raid1 is mirror, so Disk A -> B
Which is kinda stupid with 4 drives, and the FS can only be maxed to the size of a single disk.

So creating a 3 TB Raid1 is impossible.
What I need is a Raid5 or Raid6.

I continue with a Raid6, as it is "almost" the same as a Raid1, compared to the fault tolerance.

So yeah, I should go to bed now, but I want to have this server ready today

derchris
18-08-2009, 00:04
Hmm, looks like there is some kind of limit, or I'm doing something wrong.
I'm now in the CentOS install screen, and have all my 4 HDDs prepared, means I created a partition of type Software Raid. When I then try to create a Raid 1 out of all 4 drives, I'm still presented with a 1.5 TB big md device.
However, I can see full space available with a Raid 0.

Is there some kind of md Raid 1 limit ?

gigabit
17-08-2009, 21:45
Quote Originally Posted by Myatu

As for 4x 4GB swap, that is a bit much.
It just a "bug" in the manager. The end product will only be 4GB (not 16GB) but its trying to tell you its split among 4 disks - using raid 0.

DedicatedPros
17-08-2009, 21:42
You'll have to wait till tomorrow morning, and hope that they read this thread. I'd phone them, or at the least email.

derchris
17-08-2009, 21:38
And thats the problem.
The standard layout seems to only use 2 out of 4 HDDs to create the SoftRaid.
But at least I can see the disks in fdisk.
As there won't be a quick fix for this, I will do a remote install of a clean CentOS.

But please OVH, fix the Partitioning in the Manager.

Myatu
17-08-2009, 21:25
Quote Originally Posted by derchris
PHP Code:
    Type     File system     Mountpoint     RAID     Size     
1     primary     ext3         
/boot          1     100 MB
2     primary     ext3         
/              1     1495900 MB
3     primary     swap         none           
-     4 x 4000 MB 
That's not right. You should have 3TB with RAID 1, not 1.5TB.

As for 4x 4GB swap, that is a bit much. Should be something along the lines of 4x 1GB (You have 2 GB RAM, general rule of thumb is that swap should be 2x the size of RAM - so 4 GB).

You can see the arrays with ls /dev/md? and then getting more details with mdadm --detail /dev/mdN (where N is one of the arrays, ie., /dev/md1). It'll show which harddrive partitions are used to build the array (ie., /dev/sda1, /dev/sdb1), raid level, etc. Ie., an output on a SP Best-Of:

Code:
# mdadm --detail /dev/md2
/dev/md2:
        Version : 00.90
  Creation Time : Sun Jun 14 04:00:43 2009
     Raid Level : raid1
     Array Size : 707896128 (675.10 GiB 724.89 GB)
  Used Dev Size : 707896128 (675.10 GiB 724.89 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Mon Aug 17 20:24:01 2009
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           UUID : 55fd0c21:edb7ba97:f4b67177:f022a824
         Events : 0.24

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2

derchris
17-08-2009, 21:14
So, if I select Raid 0 for the 2nd Partition, I see 4 x and then the value I selected for this Partition.
With Raid 1 I only see what is left from my 1.5 TB after creating the /boot Raid 1 Partition.

Can someone from OVH please have a look into this as this doesn't seem to be right.

DedicatedPros
17-08-2009, 21:08
Quote Originally Posted by gigabit
/boot can only be raid1, after than you can make raid0 paritions.
Typo That's what I meant, raid1

derchris
17-08-2009, 21:08
Again, I don't want a Raid 0.

Tried it again, doesn't seem to work.
The 2nd Partition can only be the Root Partition.
But I only have whatever is left after creating the /boot Partition.

There is something not working correctly.
Looks like remote time

gigabit
17-08-2009, 21:03
/boot can only be raid1, after than you can make raid0 paritions.

derchris
17-08-2009, 20:58
I don't want Raid 0. But I will try to use a different order.
Even though I wasn't able to create a Swap partition before the Root partition.
Maybe I need to have /boot as a Raid 0 ?

DedicatedPros
17-08-2009, 20:52
If you want to get RAID0, you need to do this: (btw I had this problem too, the manager is just a bit off than what you'd expect)

1. Add the /boot partition first and the proper space, let's say 1000MB(it will have to be RAID 1)
2. Add the swap partition and its size, for example 4096MB (I believe this is what it will take from every drive, hence the 4x)
3. Now select the mountpoint as /, choose RAID 0 from the drop down, and leave the space thing alone

Go to the next step and it should show something like this:
Code:
       Type       File system     Mountpoint     RAID     Size     
1     primary     ext3                 /boot        1         1000     MB
2     primary     swap                none         -         4 x 4096 MB
3     primary     ext3                 /           0         4 x 1433654 MB (not sure exactly how much this will be, but around 1.3-1.4TB)

derchris
17-08-2009, 20:44
Is there something wrong with the Partitioning from the Mamager when trying to re-install the SP Storage?

It should have 4x1.5 TB.
Even with Raid 1, I should have 3 TB available.
So I selected Raid Partitioning, and was presented with only 1.5 TB.

This is the layout I could have now installed on my box:

PHP Code:
    Type     File system     Mountpoint     RAID     Size     
1     primary     ext3         
/boot          1     100 MB
2     primary     ext3         
/              1     1495900 MB
3     primary     swap         none           
-     4 x 4000 MB 
And whats this 4x Swap space about.
Is there something wrong with the Manager, or do I really need to re-configure it once the system is setup.
Or even use the resuce to do a remote install ?