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Message-Id: <250D8AFB-6442-4399-BBC5-2B37B5EC9B4B@whamcloud.com>
Date: Thu, 2 Aug 2012 22:28:20 -0700
From: Andreas Dilger <adilger@...mcloud.com>
To: Yongqiang Yang <xiaoqiangnk@...il.com>
Cc: Justin Maggard <jmaggard10@...il.com>,
ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: resize2fs > 16TB questions
On 2012-08-02, at 19:36, Yongqiang Yang <xiaoqiangnk@...il.com> wrote:
> In my memory, meta_bg is not allowed to set with resize_inode. So if
> you want to use the patch, you need options
> meta_bg,64bit,^resize_inode when mkfs.
It is already default to disable resize_inode when 64bit is enabled, but possibly this is only some for filesystems over 16TB.
It might make sense to disable resize_inode when the filesystem is resized to 16TB by resize2fs.
> I am busy on other things, so
> I am a way the patch for a while.
>
> On Fri, Aug 3, 2012 at 4:57 AM, Justin Maggard <jmaggard10@...il.com> wrote:
>> On Thu, Aug 2, 2012 at 1:15 PM, Andreas Dilger <adilger@...mcloud.com> wrote:
>>>
>>> On 2012-07-29, at 12:08, Arne Hüggenberg <hueggenberg@...rtsandbytes.de> wrote:
>>>
>>>> On Jul 29, 2012, at 8:30 PM, Andreas Dilger wrote:
>>>>>>> Unfortunately, the group descriptor size is not printed.
>>>>>>
>>>>>> how can i get the group descriptor size?
>>>>>
>>>>> Possibly with "debugfs stats"?
>>>>
>>>> ~ # debugfs /dev/vg0/lvol1
>>>> debugfs 1.42.4 (12-June-2012)
>>>> debugfs: stats
>>>> debugfs: stats
>>>>
>>>> Filesystem volume name: <none>
>>>> Last mounted on: /home/filestore_extern_1
>>>> Filesystem UUID: 8fba4f1b-5311-4c9b-b8bf-def4957dc1bd
>>>> Filesystem magic number: 0xEF53
>>>> Filesystem revision #: 1 (dynamic)
>>>> Filesystem features: has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
>>>> Filesystem flags: signed_directory_hash
>>>> Default mount options: user_xattr acl
>>>> Filesystem state: clean
>>>> Errors behavior: Continue
>>>> Filesystem OS type: Linux
>>>> Inode count: 521011200
>>>> Block count: 4168089600
>>>> Reserved block count: 191127425
>>>> Free blocks: 2162482117
>>>> Free inodes: 520936736
>>>> First block: 0
>>>> Block size: 4096
>>>> Fragment size: 4096
>>>> Reserved GDT blocks: 60
>>>> Blocks per group: 32768
>>>> Fragments per group: 32768
>>>> Inodes per group: 4096
>>>> Inode blocks per group: 256
>>>> RAID stride: 16
>>>> RAID stripe width: 160
>>>> Flex block group size: 16
>>>> Filesystem created: Fri Jul 27 17:16:24 2012
>>>> Last mount time: Sun Jul 29 15:22:23 2012
>>>> Last write time: Sun Jul 29 20:50:44 2012
>>>> Mount count: 6
>>>> Maximum mount count: -1
>>>> Last checked: Fri Jul 27 17:16:24 2012
>>>> Check interval: 0 (<none>)
>>>> Lifetime writes: 7662 GB
>>>> Reserved blocks uid: 0 (user root)
>>>> Reserved blocks gid: 0 (group root)
>>>> First inode: 11
>>>> Inode size: 256
>>>> Required extra isize: 28
>>>> Desired extra isize: 28
>>>> Journal inode: 8
>>>> Default directory hash: half_md4
>>>> Directory Hash Seed: ef2ec72a-750b-4822-bd8d-9117faadeaee
>>>> Journal backup: inode blocks
>>>> Directories: 6392
>>>> Group 0: block bitmap at 2049, inode bitmap at 2065, inode table at 2081
>>>> 26585 free blocks, 4085 free inodes, 2 used directories, 4084 unused inodes
>>>> [Checksum 0x7d46]
>>>> Group 1: block bitmap at 2050, inode bitmap at 2066, inode table at 2337
>>>> 4634 free blocks, 4096 free inodes, 0 used directories, 4096 unused inodes
>>>> [Inode not init, Checksum 0x97aa]
>>>> Group 2: block bitmap at 2051, inode bitmap at 2067, inode table at 2593
>>>> 1020 free blocks, 4096 free inodes, 0 used directories, 4096 unused inodes
>>>> [Inode not init, Checksum 0x571f]
>>>> Group 3: block bitmap at 2052, inode bitmap at 2068, inode table at 2849
>>>> 2047 free blocks, 4096 free inodes, 0 used directories, 4096 unused inodes
>>>
>>> Surprisingly, the group descriptor size is also not printed here. Looking at the code in mke2fs, it appears the 64-byte size used for filesystems when the 64bit flag is set, regardless of what size the filesystem is, and there is no way to change it.
>>>
>>> It looks like my theory is wrong, but I don't have access to a system to test this. Probably worthwhile to ask Yongqiang Yang (CC'd), who wrote the 64-bit resize code.
>>>
>>
>> I had the same confusion 11 months ago, when the 64-bit resize
>> patchset was first posted, and I posted almost the same question here.
>> My understanding at the end of the mailing list discussion was that
>> you still cannot resize your filesystem beyond 16TB -- even if the
>> 64bit flag is set -- and you may never be able to do so on that
>> filesystem because you are using resize_inode and not meta_bg. There
>> was a patchset posted on this list a few months ago by Yongquiang Yang
>> to do meta_bg expansion, but there hasn't been much action around it
>> from what I have seen (maybe for the 3.7 merge window?).
>>
>> You can read on here:
>> http://permalink.gmane.org/gmane.comp.file-systems.ext4/27718
>>
>> -Justin
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>
>
>
> --
> Best Wishes
> Yongqiang Yang
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