RHEL5 ext3 vs ext4

Latest response

Hi All,

I'm looking for some timing figures regarding fsck and ext3

I've been asked to add another 6.5TB to an existing 5.8TB LV.

Before I tell the customer go away and multiply, I'd like to find out how long it would take to FSCK a 12TB ext3 filesystem and if there are any LVM issues before recommending recreating the filesystem using ext4. (which will create at least a days downtime to restore the data), where as sticking with ext3, no downtime at all. (until the next reboot)

~~~
[root@host]# df -h /u[1-2]00
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/DBGroup27-Data27
5.8T 4.8T 767G 87% /u100
/dev/mapper/DBGroup27-Backup27
985G 545G 390G 59% /u200

[root@host]# pvs
PV VG Fmt Attr PSize PFree
/dev/emcpowera1 DBGroup27 lvm2 a-- 499.99G 0
/dev/emcpowerbk1 DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbl DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbm DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbn DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbo DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbp DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbq DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbr DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbs DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbt DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbu DBGroup27 lvm2 a-- 500.00G 0
/dev/emcpowerbv DBGroup38 lvm2 a-- 500.00G 0
/dev/emcpowerbw DBGroup38 lvm2 a-- 500.00G 0
/dev/emcpowerbx DBGroup38 lvm2 a-- 500.00G 0
/dev/emcpowerby DBGroup38 lvm2 a-- 500.00G 0
/dev/emcpowerbz DBGroup38 lvm2 a-- 500.00G 0
/dev/emcpowerq1 DBGroup27 lvm2 a-- 499.99G 0
/dev/emcpowerr1 DBGroup27 lvm2 a-- 499.99G 0
/dev/emcpowers1 DBGroup38 lvm2 a-- 499.99G 0
/dev/emcpowert1 DBGroup38 lvm2 a-- 499.99G 0
/dev/sda2 VolGroup00 lvm2 a-- 135.62G 0
/dev/sdb1 VolGroup00 lvm2 a-- 836.59G 0
[root@host]# vgs
VG #PV #LV #SN Attr VSize VFree
DBGroup27 14 2 0 wz--n- 6.84T 0
DBGroup38 7 2 0 wz--n- 3.42T 0
VolGroup00 2 8 0 wz--n- 972.22G 0
[root@host]#
~~~

Regards
Jonathan

Responses

I'd like to find out how long it would take to FSCK a 12TB ext3 filesystem

This depends on usage of the filesystem. A blank 12TiB filesystem would probably fsck quite quickly ;)

However with some sensible usage, I wouldn't expect under a month. The ext4 tools (yum install e4fsprogs) may be able to fsck it faster, but whether that is hours or days is difficult to predict.

I would strongly encourage your customer to not use such large filesystems on RHEL5, the check times make it risky.

If it's an option for you, RHEL 6 and 7 with their later ext4 drivers and tools are significantly faster.

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