Re: Questions about RAID 6
Mark Allums put forth on 4/27/2010 10:31 PM:
> For DIY, always pair those drives. Consider RAID 10, RAID 50, RAID 60,
> etc. Alas, that doubles the number of drives, and intensely decreases
> the MTBF, which is the whole outcome you want to avoid.
This is my preferred mdadm 4 drive setup for a light office server or home
media/vanity server. Some minor setup details are omitted from the diagram
to keep it simple, such as the fact that /boot is a mirrored 100MB partition
set and that there are two non mirrored 1GB swap partitions. / and /var are
mirrored partitions in the remaining first 30GB. These sizes are arbitrary,
and can be seasoned to taste. I find these sizes work fairly well for a non
GUI Debian server.
md raid, 4 x 500GB 7.2K rpm SATAII drives:
mirror mirror
/ \ / \
-------- 3 -------- -------- 3 --------
| /boot | 0 | /boot | | swap1 | 0 | swap2 |
| / | G | / | | /var | G | /var |
|--------| |--------| |--------| |--------|
| /home | | /home | | /home | | /home |
| /samba | | /samba | | /samba | | /samba |
| other | | other | | other | | other |
| | | | | | | |
| | | | | | | |
-------- -------- -------- --------
\ \ / /
-------------------------------
RAID 10
940 GB NET
For approximately the same $$ outlay one could simply mirror two 1TB 7.2K
rpm drives and have the same usable space and a little less power draw. The
4 drive RAID 10 setup will yield better read and write performance due to
the striping, especially under a multiuser workload, and especially for IMAP
serving of large mailboxen. For a small/medium office server running say
Postfix/Dovecot/Samba/lighty+Roundcube webmail, a small intranet etc, the 4
drive setup would yield significantly better performance than the higher
capacity 2 drive setup. Using Newegg's prices, each solution will run a
little below or above $200.
This 4 drive RAID 10 makes for a nice little inexpensive and speedy setup.
1TB of user space may not seem like much given the capacity of today's
drives, but most small/medium offices won't come close to using that much
space for a number of years, assuming you have sane email attachment policies.
--
Stan
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