[CentOS] ssd quandry

Sun Oct 23 07:48:41 UTC 2011
John R Pierce <pierce at hogranch.com>

On 10/23/11 12:23 AM, Ken godee wrote:
> Maybe try to partition it to see what happens.

with parted at least, I'm stuck with a vicious circle that won't let me 
align the data right?

# parted /dev/sdc
GNU Parted 2.1
Using /dev/sdc
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel msdos
Warning: The existing disk label on /dev/sdc will be destroyed and all 
data on this disk will be lost. Do you want to continue?
Yes/No? y
(parted) mkpart primary ext4 512k -1s
Warning: The resulting partition is not properly aligned for best 
performance.
Ignore/Cancel? i
(parted) quit

# mkfs.ext4 /dev/sdc1
mke2fs 1.41.12 (17-May-2010)
/dev/sdc1 alignment is offset by 4096 bytes.
This may result in very poor performance, (re)-partitioning suggested.
Filesystem label=
OS type: Linux
Block size=8192 (log=3)
Fragment size=8192 (log=3)
Stride=1 blocks, Stripe width=0 blocks
12210528 inodes, 24413127 blocks
1220656 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4311218176
373 block groups
65528 blocks per group, 65528 fragments per group
32736 inodes per group
Superblock backups stored on blocks:
         65528, 196584, 327640, 458696, 589752, 1638200, 1769256, 3210872,
         5307768, 8191000, 15923304, 22476104

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 22 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

# mount -t ext4 /dev/sdc1 /ssd
mount: wrong fs type, bad option, bad superblock on /dev/sdc1,
        missing codepage or helper program, or other error
        In some cases useful info is found in syslog - try
        dmesg | tail  or so


# tail /var/log/messages
....
Oct 23 00:27:43 svfis-dl180b kernel: EXT4-fs (sdc1): bad block size 8192




GRRR  ok.  um.


# parted /dev/sdc
GNU Parted 2.1
Using /dev/sdc
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) unit b
(parted) print
Model: HP LOGICAL VOLUME (scsi)
Disk /dev/sdc: 199992852480B
Sector size (logical/physical): 512B/8192B
Partition Table: msdos

Number  Start    End            Size           Type     File system  Flags
  1      512000B  199992852479B  199992340480B  primary  ext4

(parted) rm 1
(parted) mkpart primary ext4 1024s -1s
Warning: The resulting partition is not properly aligned for best 
performance.
Ignore/Cancel? y
parted: invalid token: y
Ignore/Cancel? ignore
(parted) print
Model: HP LOGICAL VOLUME (scsi)
Disk /dev/sdc: 199992852480B
Sector size (logical/physical): 512B/8192B
Partition Table: msdos

Number  Start    End            Size           Type     File system  Flags
  1      524288B  199992852479B  199992328192B  primary

(parted) quit

# mkfs.ext4 /dev/sdc1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=8192 (log=3)
Fragment size=8192 (log=3)
Stride=1 blocks, Stripe width=0 blocks
12210528 inodes, 24413126 blocks
1220656 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4311218176
373 block groups
65528 blocks per group, 65528 fragments per group
32736 inodes per group
Superblock backups stored on blocks:
         65528, 196584, 327640, 458696, 589752, 1638200, 1769256, 3210872,
         5307768, 8191000, 15923304, 22476104

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

*and, yup, 8K blocks still won't mount*

so...

# mkfs.ext4 -b 4096 -F /dev/sdc1
mke2fs 1.41.12 (17-May-2010)
Warning: specified blocksize 4096 is less than device physical 
sectorsize 8192, forced to continue
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
                   ^^^^^^
...


fixes it.  have to use -F to format this thing.   now I''m seeing IO 
more like what I'd expect to see.


-- 
john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast