any use for lsm with a raid card?

any use for lsm with a raid card?

Post by news-server.triad.rr.co » Tue, 24 Jun 2003 07:59:06



This is a gut-check for me as I've minimal playtime with LSM. The only
thing I ever learned from messing with it was its usage interfering with
btcreate if used on a root volume. I have an ES45 I'm preparing to build
up. The only physical disks will be boot volumes. I have 6 disks
attached to a smartarray 5300, all 18GB. two will be a raid-1 mirror for
boot, two may be standalone swap (mirrored?) and two will probably be
local scratch, or hot spares. i only have 1 6-drive cage at this moment,
so no two channel scsi for now. everything else will be on emc via fiber
channel.

so.. with such a setup is there any real use for lsm? I don't think so,
but as I said I don't know much about the product.

reply to list; the email addr is a spamtrap.

thx,

-r

 
 
 

any use for lsm with a raid card?

Post by Nikola Milutinovi » Tue, 24 Jun 2003 15:51:14



Quote:> This is a gut-check for me as I've minimal playtime with LSM. The only
> thing I ever learned from messing with it was its usage interfering with
> btcreate if used on a root volume. I have an ES45 I'm preparing to build
> up. The only physical disks will be boot volumes. I have 6 disks
> attached to a smartarray 5300, all 18GB. two will be a raid-1 mirror for
> boot, two may be standalone swap (mirrored?) and two will probably be
> local scratch, or hot spares. i only have 1 6-drive cage at this moment,
> so no two channel scsi for now. everything else will be on emc via fiber
> channel.

> so.. with such a setup is there any real use for lsm? I don't think so,
> but as I said I don't know much about the product.

The only situation that would require LSM over hardware RAID, that I'm aware
of, would be when you have multiple RAID controllers and would like to have
them as a single device. The alternative would be to use AdvFS volume
balancing.

Nix.

 
 
 

any use for lsm with a raid card?

Post by Alan Rollow - Dr. File System's Home for Wayward Inode » Wed, 25 Jun 2003 01:23:15



Quote:>This is a gut-check for me as I've minimal playtime with LSM. The only
>thing I ever learned from messing with it was its usage interfering with
>btcreate if used on a root volume. I have an ES45 I'm preparing to build
>up. The only physical disks will be boot volumes. I have 6 disks
>attached to a smartarray 5300, all 18GB. two will be a raid-1 mirror for
>boot, two may be standalone swap (mirrored?) and two will probably be
>local scratch, or hot spares. i only have 1 6-drive cage at this moment,
>so no two channel scsi for now. everything else will be on emc via fiber
>channel.

>so.. with such a setup is there any real use for lsm? I don't think so,
>but as I said I don't know much about the product.

If internal limitations of the particular array controller limit
the performance of a single logical unit, but allow greater
aggregate performance of two units, even on the same controller
LSM will let you build that aggregate; a stripe set set built
from mirrors.  An LSM mirror built from controller stripe, RAID-5
or more mirrors.

Generally, for a configuration this limited, LSM is an extra
layer that needs more management than it offers in value.  Something
you might consider is building the local swap as a stripe set and
then use LSM to mirror it to the EMC array.  I don't know how
feasible or desirable it is doing the same for the root file
system.

Quote:

>thx,

>-r

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