maximum partition size...

Cris Rhea crhea at
Tue Apr 18 09:05:26 CDT 2006

The limiting factor is the max size of a partition using MBR for the partition table.

To use larger disks (and larger partitions), you need to go to GPT for the partition table.
Not really a big deal to do, as parted handled it nicely.

I did a quick search and found a Dell whitepaper on the topic:

I'm currently running CentOS4 (RHEL4) on a Western Scientific Fusion storage
server (24 x 400GB SATA drives on an Areca RAID controller):

[root at rcfcluster-nfs2 ~]# df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/hda5               489992    198171    266521  43% /
/dev/hda1               147764     12904    127231  10% /boot
none                   1965424         0   1965424   0% /dev/shm
/dev/hda10            66548312  20975100  42192736  34% /local1
/dev/hda9               988212     17708    920304   2% /tmp
/dev/hda7              5771468   3195724   2282560  59% /usr
/dev/hda8               988212    557752    380260  60% /var
/dev/sda2            2113787824 257549640 1748864004  13% /home
/dev/sda1            4227573652 839892152 3344731832  21% /data
/dev/sda3            2117534300    104452 2009865256   1% /scratch

FYI-- These are all EXT3 file systems-- nothing fancy there.


-- Cris

> Hi all,
> We're running several Dell PowerEdge 1850 servers with RHEL3 U7 and
> RHEL3 U3, some of them running the i686 version, others running the
> x86_64 version.
> We use an iSCSI array for data storage, only the server OS is stored
> on the local HD.
> Some of the servers use the Linux iSCSI initiator (software), while
> others use the QLogic iSCSI HBA (hardware).
> We usually create a pretty big volume (several TBs) on the iSCSI array
> and then create one or more (up to 4) primary partitions on it.
> We use the standard partion table (MS-DOS), not the new one (GPT).
> We use use ext3 as filesystem type.
> What is the maximum partition size that we can safely use in such environment?
> I found a good resource about system configuration limits on the RH web site:
> Unfortunately  it doesn't include the maximum partition size, though
> it includes  the maximum filesystem size. Can I safely assume that the
> first value is equal to the latter?
> IIRC, I read somewhere that the maximum partition size is 2TB.
> If so, how does RHEL4 support 8TB partitions, as per their web site?
> Also, we've the ability to create a filesystem directly on the iSCSI
> volume without creating a partition at all, e.g. mkfs.ext3 /dev/sdb
> instead of mkfs.ext3 /dev/sdb1.
> I don't know if that is possible with a regular HD at all, it appears
> to work fine with an iSCSI volume.
> What are the pros and the cons of creating a filesystem w/o a partition?

 Cristopher J. Rhea                     Mayo Foundation
 Research Computing Facility             Pavilion 2-25
 crhea at Mayo.EDU                        Rochester, MN 55905
 (507) 284-0587                        Fax: (507) 284-5231

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