[CentOS] Seeking pointers to info about LVM migration and performance
barton.schaefer at gmail.com
Sun Jul 8 19:39:10 UTC 2007
On 7/8/07, Johnny Hughes <johnny at centos.org> wrote:
> Well ... if you are using hardware RAID, then striping LVM will likely
> not give you any benefit speed wise. (Unless multiple controllers are
> used and read/write can be done in parallel).
> The speed benefit happens if LVM can stripe the sectors to SATA or SCSI
> drives where simultaneous read/writes can happen. With hardware RAID,
> the controller normally handles all that, so LVM striping is not
> normally done.
What we have is a hardware RAID enclosure that already has all the
drives it can handle, and is approaching capacity. So what we're
currently considering is adding an entire additional RAID device and
using LVM to combine them into a VG as a pair of SCSI drives. So it
appears we could configure them as either striped or linear, and LVM2
would handle growing even a striped configuration if we add a third
A performance boost from LVM striping would be a bonus, but what I'm
really asking is whether there's a penalty for LVM linear.
I hadn't considered, though, that we could also rotate larger drives
into the existing RAID and then grow the filesystem once they were all
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