I agree with Simon.
When you are talking about a couple of Terabytes, most Raid Arrays effectively
have their own LVM built in.
Generally, software LVM is just needed for 2 features:
Snapshots: This is available in many Raid systems, but it can be a fairly
expensive option, so many people prefer software snapshots. Since XFS does not
to my knowledge directly support snapshots, one is left to consider a software
LVM vs. paying for the hardware option.
Mirroring between Raid Arrays: Some truly paranoid people use LVM to mirror 2
standalone Raid Arrays to together. This is pretty rare because it is very
expensive to do. I doubt you are planning on doing this.
You mention volume growth in your e-mail, put that is typically done in
hardware when you are talking about a 2 Terabyte array.
Greg Freemyer
>> Marek.Les@xxxxxxxxxxxxxxx schrieb:
>> >
>> > Hi there,
>> >
>> > Our company is in the process of moving the production server data on a
>> > enterprise storage servers and therefore we are considering which setup
>> > would have the best performance and stability at the same time. Our
>> > preliminary tests showed us that, at the filesystem level, XFS performs
>> > best. Unfortunately, to be capable of growing the volumes we need to add
>> > another layer - the volume manager. This increases the chances for
>> > something to go wrong.
>> > As I've read through the mailing list and other sources, there are only
>> two
>> > possible software packages on Linux - LVM and EVMS. From what I've read
>> I
>> > understood that LVM 1.x is feature-frozen and maybe even bugsolve-frozen
>> in
>> > favor of LVM2 development (see the deadlock while using xfs_freeze
>> issue).
>> > LVM 2.x is unstable beta and EVMS is so fresh that no real experience
>> has
>> > been heard of.
>> > I understand that there's no bug-free software and no guarantee of
>> anything
>> > but maybe some of you have some enterprise-level experience with, say,
>> 2+
>> > TB data pool on XFS and some volume manager. I appreciate any reference
>> of
>> > any kind, some known imcompatibilies, what mistakes to avoid.. it would
>> > help me a lot.
>> I don't know the kind of storage you're going to use. There are ways to
>> create blockdevices which you can enlarge later, for example a linear
>> array where you just concatenate disks, or with some hardware RAID or
>> high end storage solution. It's then the same procedure like having a
>> 100G disk with only one partition of 20G. You can enlarge (delete and
>> create the larger one with the same starting point) this partition to
>> 40G and just grow the (still existing) xfs volume on it.
>> It's my dirty but safe way of doing Logical Volume Management :)
>> Simon
>> >
>> > With best regards,
>> >
>> > Marek Les
>> > Seznam.cz
>> >
>> > Note: If you don't want to discuss this theme in public, please don't
>> > hesitate to write me directly :-)
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