| Summary: | LVM2 Quick Install Guide: improvement - warn about existence and limits of LVM physical extent (PE) | ||
|---|---|---|---|
| Product: | [OLD] Docs on www.gentoo.org | Reporter: | Martin Rejman <martin.rejman> |
| Component: | Other documents | Assignee: | Docs Team <docs-team> |
| Status: | RESOLVED INVALID | ||
| Severity: | minor | ||
| Priority: | High | ||
| Version: | unspecified | ||
| Hardware: | x86 | ||
| OS: | Linux | ||
| URL: | http://www.gentoo.org/doc/en/gentoo-x86+raid+lvm2-quickinstall.xml | ||
| Whiteboard: | |||
| Package list: | Runtime testing required: | --- | |
Are you asking for support with an LVM issue? If so, please check the forums or the mailing lists, as Bugzilla is not a user support venue. If you have a specific change that you think should be made to the documentation, please post it, either as a GuideXML patch or as a plain text paragraph. It's hard for us to understand what you're asking. Thanks. lvm.conf has the following: # The default metadata format that commands should use - "lvm1" or "lvm2". # The command line override is -M1 or -M2. # Defaults to "lvm2". # format = "lvm2" (In reply to comment #0) > As I was following this guide for LVM2, and still the limit mentioned above > applies, is there a way to choose LVM2 metadate format ? The limit does NOT apply. See the lvm.conf where the default for at least the last 3 years has been the lvm2 metadata format. If your system is using the lvm1 metadata format, you'll need to trace why it's doing so, as that format has a number of other problems. My personal & work systems are definitely using the lvm2 format, and I've got some LVs with well more than 64k extents: --- Logical volume --- LV Name /dev/vg/(censored) VG Name vg LV UUID I0GouC-M3Ct-nWJX-OhNy-9yXN-ufpf-UKdKc2 LV Write Access read/write LV Status available # open 1 LV Size 450.00 GiB Current LE 115200 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 254:8 |
Since I have a large disc space, I had to do the LVM setup one more time. I had to set the physical extent (PE) to a bigger value than the default, 4MB ... I used 64M. I think it is worth mentioning it in the guide, since once you do the "vgcreate", you can not change the value of the PE easily. Or is there a way of As `man vgcreate` says: If the volume group metadata uses lvm1 format, extents can vary in size from 8KB to 16GB and there is a limit of 65534 extents in each logical volume. The default of 4 MB leads to a maximum logical volume size of around 256GB. If the volume group metadata uses lvm2 format those restrictions do not apply, but having a large number of extents will slow down the tools but have no impact on I/O performance to the log- ical volume. The smallest PE is 1KB. As I was following this guide for LVM2, and still the limit mentioned above applies, is there a way to choose LVM2 metadate format ? Reproducible: Always Actual Results: Trouble when used on large disc. Expected Results: A warning in the guide one has to think about the PE limit, or, how to use LVM2 metadata format, which should eliminate the limits.