I have one LVG with one LV consisting of several physical drives, ranging from 500G to 3T, with a total size of 6.5T, formatted with ext4.
After I boot the system, when anything writes a file to that LV, the write hangs for 1 minute or more, then continues at full speed with no errors. Some apps, though can't handle the delay, and report that the write fails.
This does not occur with a small file ( < 50M or so ). But the first time a larger file is written, then the delay. And this delay occurs only one time.
I have noticed something similar in the past with smaller LVs ( < 1T ), but the delay was insignificant then. But as I grew this LV, the delay increased.
I can run e2fsck on the LV, and even optimize directories (-D option), with no delay occurring.
I have tried googling, but have not found any mention of something like this (maybe not using the right key words?). So, does this sound familiar to any LVM experts out there? Any suggestions?
FWIW: I'm currently running Fedora 17 (64 bit), kernel 3.8.4-102.fc17.x86_64 (although I have seen this problem on 32 bit kernels/machines as well). I have 4 physical drives (500G, 1T, 1.5T, 3T), and non-raid configured.
Some other info:
[root elmer ken]# lvmdiskscan
/dev/vg_elmer/lv_swap [ 3.62 GiB]
/dev/sda1 [ 500.00 MiB]
/dev/vg_elmer/lv_root [ 23.81 GiB]
/dev/sda2 [ 27.47 GiB] LVM physical volume
/dev/VG_NAS/LV_NAS [ 5.46 TiB]
/dev/sdb1 [ 2.73 TiB] LVM physical volume
/dev/sdc1 [ 465.76 GiB] LVM physical volume
/dev/sdd1 [ 931.51 GiB] LVM physical volume
/dev/sde1 [ 1.36 TiB] LVM physical volume
0 LVM physical volume whole disks
5 LVM physical volumes
[root elmer ken]# lvdisplay
--- Logical volume ---
LV Path /dev/VG_NAS/LV_NAS
LV Name LV_NAS
VG Name VG_NAS
LV UUID IO93PY-kFF2-19u7-33lX-m7Mg-8BZC-q12ttn
LV Write Access read/write
LV Creation host, time ,
LV Status available
# open 1
LV Size 5.46 TiB
Current LE 1430794
Read ahead sectors auto
- currently set to 256
Block device 253:2
[root elmer ken]#