array size

array size

[Sharif Islam]

Shouldn't the size of the array be around 760GB? It says spare device 0.

/dev/md0:
        Version : 00.90.01
  Creation Time : Mon Dec 12 15:56:58 2005
     Raid Level : raid5
     Array Size : 586075008 (558.92 GiB 600.14 GB)
    Device Size : 195358336 (186.31 GiB 200.05 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Tue Dec 13 09:59:54 2005
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

Re: array size

[Ming Zhang]

4 disks, 0 spare, so 3x capacity

586075008 = 3 x 195358336

ming


On Tue, 2005-12-13 at 10:01 -0600, Sharif Islam wrote:
> Shouldn't the size of the array be around 760GB? It says spare device 0.
> 
> /dev/md0:
>         Version : 00.90.01
>   Creation Time : Mon Dec 12 15:56:58 2005
>      Raid Level : raid5
>      Array Size : 586075008 (558.92 GiB 600.14 GB)
>     Device Size : 195358336 (186.31 GiB 200.05 GB)
>    Raid Devices : 4
>   Total Devices : 4
> Preferred Minor : 0
>     Persistence : Superblock is persistent
> 
>     Update Time : Tue Dec 13 09:59:54 2005
>           State : clean
>  Active Devices : 4
> Working Devices : 4
>  Failed Devices : 0
>   Spare Devices : 0
> 
> 
> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: array size

[Mark Overmeer]

* Ming Zhang (mingz@ele.uri.edu) [051213 16:15]:
> 4 disks, 0 spare, so 3x capacity
> 586075008 = 3 x 195358336
> 
> On Tue, 2005-12-13 at 10:01 -0600, Sharif Islam wrote:
> > Shouldn't the size of the array be around 760GB? It says spare device 0.

> > /dev/md0:
> >         Version : 00.90.01
> >   Creation Time : Mon Dec 12 15:56:58 2005
> >      Raid Level : raid5
> >      Array Size : 586075008 (558.92 GiB 600.14 GB)
> >     Device Size : 195358336 (186.31 GiB 200.05 GB)

The description of the field is a little confusing.  It should read
"Netto Array Size" or "Available Disk Space" or some.  Then it is clear
that the last disk is excluded from the shown size.
-- 
Regards,

               MarkOv

------------------------------------------------------------------------
       Mark Overmeer MSc                                MARKOV Solutions
       Mark@Overmeer.net                          solutions@overmeer.net
http://Mark.Overmeer.net                   http://solutions.overmeer.net

RE: array size

[Guy]

The last disk is not excluded, since the excluded space is used for parity
(xor).

An equal part of all disks is excluded (the parity data).

However, the size is the same as 1 disk being excluded.  :)

> -----Original Message-----
> From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
> owner@vger.kernel.org] On Behalf Of Mark Overmeer
> Sent: Tuesday, December 13, 2005 12:10 PM
> To: Ming Zhang
> Cc: Sharif Islam; linux-raid@vger.kernel.org
> Subject: Re: array size
> 
> * Ming Zhang (mingz@ele.uri.edu) [051213 16:15]:
> > 4 disks, 0 spare, so 3x capacity
> > 586075008 = 3 x 195358336
> >
> > On Tue, 2005-12-13 at 10:01 -0600, Sharif Islam wrote:
> > > Shouldn't the size of the array be around 760GB? It says spare device
> 0.
> 
> > > /dev/md0:
> > >         Version : 00.90.01
> > >   Creation Time : Mon Dec 12 15:56:58 2005
> > >      Raid Level : raid5
> > >      Array Size : 586075008 (558.92 GiB 600.14 GB)
> > >     Device Size : 195358336 (186.31 GiB 200.05 GB)
> 
> The description of the field is a little confusing.  It should read
> "Netto Array Size" or "Available Disk Space" or some.  Then it is clear
> that the last disk is excluded from the shown size.
> --
> Regards,
> 
>                MarkOv
> 
> ------------------------------------------------------------------------
>        Mark Overmeer MSc                                MARKOV Solutions
>        Mark@Overmeer.net                          solutions@overmeer.net
> http://Mark.Overmeer.net                   http://solutions.overmeer.net
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Array Size

[jlewis]

On Sun, 11 Jan 2004, Sharif Islam wrote:

> I have 6 IDE hard drives, each 120 GB.
> I am bit confused by the reported array size.
> 
> # mdadm -D /dev/md0
> /dev/md0:
>         Version : 00.90.00
>   Creation Time : Fri Jan  9 13:52:20 2004
>      Raid Level : linear
>      Array Size : 703324416 (670.74 GiB 720.25 GB)

> /dev/md0              661G   33M  627G   1% /ppa
> 
> 
> Shouldn't the above be ~720GB?

It is.  That 720GB is in units of 1000's, while the 670 GiB is in units of 
1024's.  As drives get bigger, the difference in manufacturer advertised 
sizes (measured in 1000s) is getting more noticable when compared to GB 
measured in 1024s.  So, the above is telling you your 720GB is really 
670GiB, and I'm guessing you formatted it ext3 and the journal is taking 
~32mb.  That 627+33 = 660G...and you probably have 10G in reserved blocks.
 
----------------------------------------------------------------------
 Jon Lewis *jlewis@lewis.org*|  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |  
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________

RE: Array Size

[Guy]

Overhead!
If filesystem is ext3:
	Reserved for root user, default 5%
	Inodes
	Journal
	Superblocks

I don't know the exact numbers.

Why RAID0?  You lose a disk and game over!

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Sharif Islam
Sent: Sunday, January 11, 2004 10:49 PM
To: linux-raid@vger.kernel.org
Subject: Array Size

I have 6 IDE hard drives, each 120 GB.
I am bit confused by the reported array size.

# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.00
  Creation Time : Fri Jan  9 13:52:20 2004
     Raid Level : linear
     Array Size : 703324416 (670.74 GiB 720.25 GB)

[....]

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/hda1              26G  1.2G   23G   5% /
/dev/hda5             2.6G   33M  2.4G   2% /tmp
/dev/hda3             3.9G   59M  3.6G   2% /var
/dev/md0              661G   33M  627G   1% /ppa


Shouldn't the above be ~720GB?

Thanks.

-Sharif


-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Array Size

[Sharif Islam]

I have 6 IDE hard drives, each 120 GB.
I am bit confused by the reported array size.

# mdadm -D /dev/md0
/dev/md0:
        Version : 00.90.00
  Creation Time : Fri Jan  9 13:52:20 2004
     Raid Level : linear
     Array Size : 703324416 (670.74 GiB 720.25 GB)

[....]

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/hda1              26G  1.2G   23G   5% /
/dev/hda5             2.6G   33M  2.4G   2% /tmp
/dev/hda3             3.9G   59M  3.6G   2% /var
/dev/md0              661G   33M  627G   1% /ppa


Shouldn't the above be ~720GB?

Thanks.

-Sharif