Re: raid upgrade form 1.5T to 3T drives with 0.90 superblock

[Krzysztof Adamski <k@adamski.org>]

On Fri, 2011-06-24 at 00:35 -0500, Stan Hoeppner wrote:
> On 6/23/2011 1:43 PM, Krzysztof Adamski wrote:
> > Hi All,
> > 
> > I have a raid6 array made out of 8 1.5T drives and I wanted to change to
> > use 3T drives. The array is 0.90. After reading the wiki I see that 0.90
> > superblock will not work with any device larger then 2T.
> > 
> > What are my options for a live upgrade (backup/restore is not possible)?
> 
> The best way to do this, given that you have no backup, is to add a
> known-to-work-with-Linux SAS/SATA HBA and build a new md array and
> format it with a fresh filesystem.  Let the 8 new drives spin for a
> couple of days.  If all 8 drives are still kicking, copy everything over
> from the current filesystem with a 'cp -a' or similar method.  If you
> have NFS/Samba shares or other filesystem specific mappings, rsync, etc,
> edit your conf files to point to the new filesystem/device.  Run in
> production with the new array for a few days or a week to make sure it's
> working correctly, then remove the old array at your leisure.

I was afraid of this. I only have 4 empty drive bays in my Norco 4220
case, I will have to shut down the second array and remove it during the
time I'm upgrading. I will also have to get an HBA that supports 3T
drives.

> This staged multi step approach gives you the best chance to avoid data
> loss during the migration as even after it's complete you still have the
> existing array fully intact until you decide to remove it.  It is much
> safer than rebuilding an 8 disk array one disk at a time.  It also puts
> much less wear and tear on the new drives.  Another benefit is that
> after copying the files over, the new filesystem will be much less
> fragmented than in the case of rebuilding the existing array one drive
> at a time.

I have before upgrade a 5 drive array one drive at a time without
problems, but the new drives were only 2T.

> If you don't have 16 disk bays and sufficient SAS/SATA ports in your
> current chassis, and you can't leave a side panel off with the 8 new
> drives simply sitting on a desk during the transition, then you should
> grab an external enclosure, either desktop or rackmount, whichever fits
> your needs, and an external version of the HBA.  Some options are:
> 
> If you have 16 bays or can sit the new 8 drives on the desk next to the
> server during the upgrade just grab one of these cheap LSI based Intel 8
> port HBAs:
> 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16816117157

This card is based on 1068E chip, it does not support drives larger then
2T. I already have 2 LSI cards based on the same chip and I will need to
upgrade.

> 
> If you must go external, take a look at these.  A bit more costly, but a
> better solution in the long run.  It'll also allow you to keep your
> existing array instead of replacing it.  If you go with the rackmount
> unit adding a 4 port HBA in the future will allow you to add 4 more
> drives.  Each row of 4 drives has its own SFF8088 port on the back.
> 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16816118116
> http://www.newegg.com/Product/Product.aspx?Item=N82E16816111092
> http://www.newegg.com/Product/Product.aspx?Item=N82E16816133044
>