On 2010-11-14 21:50, Luca Berra wrote:
On Sun, Nov 14, 2010 at 05:36:38PM +0200, Zoltan Szecsei wrote:
*Partition alignment?
Is this relevant for modern HDs (I'm using 5900rpm Seagate 2TB drives)
for modern hdds with 4k sectors it is
new fdisk and/or parted should already know how to align
fdisk reports 512b sectors:
root@gs0:/home/geograph# fdisk -lu
WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util
fdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
256 heads, 63 sectors/track, 242251 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 63 3907024127 1953512032+ fd Linux raid
autodetect
(All 8 disks are as above)
in any case, since you want to use the whole space for raid, why create
partitions at all, md works nicely without
OK
*Chunk size:
After reading MANY different opinions, I'm guessing staying at the
default chunk size is optimal? Anyone want to add to this argument?
i believe the default in newer mdadm is fine
*After partitioning the 8 drives, is this the correct sequence?
mdadm --create /dev/md0 --metadata=1.2 --auto=md --chunk=64
--level=raid6
why you state the chunk size here, i tought you wanted to stay with the
defauklt
because on my mdadm, 64 is the default - and I was just re-enforcing
that for the reader.
root@gs0:/home/geograph# mdadm -V
mdadm - v2.6.7.1 - 15th October 2008
root@gs0:/home/geograph#
*After this, do I mkfs ext4 first, or LVM first?
if you want to use lvm it would be lvm first, but... do you want to?
there is no point if the aim is allocating the whole space to a single
filesystem.
Because I might want to join this array to another one at a later stage
- I would then have 2 boxes each with 8 drives, and each with a SiI3132
card on the same motherboard.
I might use the second box to mirror the first, or to extend it - not
sure of my needs yet.
*What stride and stripe values should I use?
new toolstack should already find the correct stripe/stride for you
How would I check ?
root@gs0:/home/geograph# mkfs.ext4 -V
mke2fs 1.41.11 (14-Mar-2010)
Using EXT2FS Library version 1.41.11
root@gs0:/home/geograph#
one more note:
for such a big array i would suggest to create a bitmap, so in case of
an unclean shutdown you do not have to wait for 27 hours for it to
rebuild. an internal bitmap will do.
Nice tip - I'll look into it - Thanks,
Zoltan
--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
P.O. Box 7, Muizenberg 7950, South Africa.
65 Main Road, Muizenberg 7945
Western Cape, South Africa.
34° 6'16.35"S 18°28'5.62"E
Tel: +27-21-7884897 Mobile: +27-83-6004028
Fax: +27-86-6115323 www.geograph.co.za
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