Les Mikesell wrote:
On Thu, 2005-01-13 at 12:08, Randall A. Jones wrote:This is a good question. In theory, I think the answer is yes, but I'm not sure about potential limitations of LVM regarding maxium number of blocks in a volume group or logical volume. I've seen messages like the following in the past (FC2 install).
This SCSI card is an Adaptec 39160.
The RAID is a Nexsan ATABoy2 with a SCSI interface.
It seems that the driver recognizes the need and is trying to use the READ(16) command but that it is failing.
from log:
sdc : very big device. try to use READ CAPACITY(16).
sdc : READ CAPACITY(16) failed.
Can you configure smaller logical partitions on the device and combine
them with LVM?
[root@aes init.d]# vgcreate -s 128 aesvg0 /dev/sdc
vgcreate -- INFO: maximum logical volume size is 2 Terabyte
vgcreate -- doing automatic backup of volume group "aesvg0"
vgcreate -- volume group "aesvg0" successfully created and activated
for LVM2, vgcreate states a maximum logical volume of 2TB.
I have not found or read satisfactory documentation yet to answer questions about
size limitations of creating a > 2TB VG or LVM.
Is anyone familiar with LVM enough to say that it will support large resulting volumes? What is the maxium size LV possible in LVM2, kernel 2.6 ?
Where is a good place to read details about the capabilities?
I have found HowTo documents to be generalized for a common case of a few "normal" sized devices joined in an LV with no information about what to do if you want a large LV.
The vgcreate man page says that you can create a PE (physical extent) up to 16GB in size and that there is a maxium of 64k PEs per LV. 16GB*64K = ~1.125 PB (PetaBytes). Is that right?
That begs the question why vgcreate talks about a 2TB limit. Legacy message? from a time before LBD in the kernel?
Perhaps I need to learn more about LVM before I make up my mind on its capabilities.
Any helpful hints or guidance would be much appreciated.
Randall
-- ..:.:::: Randall Jones GST NASA Goddard Space Flight Center HPC Visualization Support http://hpcvis.gsfc.nasa.gov Scientific Visualization Studio http://svs.gsfc.nasa.gov rajones@xxxxxxxxxxxxxxxxx Code 610.3 301-286-2239
