ML 350 G5 - hware RAID Planning for a Mail Server

[Maaz]

Machine: Proliant ML 350 G5 having 3 SATA Hard Drives with Hardware RAID 5.
Organization Type: Small/mid range(having 50-100 users)

1, for a small/midrange enterprise, is it better to install the OS(Linux/Windows) on a hware RAID5 volume, instead of hardware RAID1 ?

suggest/recommend.

2, this machine will serve as a mail server(Postfix), so recommend me the best RAID-Level for the
a, Linux OS volume
b, user's mailbox volume

I am sharing my own plan
Linux OS "/" (hware RAID-1): /dev/sda1, /dev/sdb1
user's mailboxes /var/spool/mail (hware RAID-1): /dev/sdc1, /dev/sdd1
i.e I will add one more hdd(total 4), destroy the default hw RAID-5 volume, and configure two hware RAID-1 volumes, one for the OS and the other one for the user's mailboxes.

Suggest/recommend

I think RAID-5 is not good becuase Its slow in writing(comparitively to RAID-1), and its also not recoverable if more than 2 disks fails simultaneously ... am i right ?

suggest/recommend please.

[Maaz]

3, recommended Filesystem for mailbox volume(ext3, reiserfs, or xfs)

4, recommend me the best RAID-Level and filesystem for the user's home directory.

5, If /boot is created on a separate volume, then recommend me the best FS(ext3, reiserfs, or xfs)

[skt_skt]

Here is how our stanadard setup

hardware raid(raid 5) with three or more disks ; the logical drive vsisble from OS is /dev/sda

the first partition sda1 is /boot
sda2 partition belongs to vg00 hold other OS file systems.

similarly you may keep the mail data as one LV on vg00.

As far as the reduntancy is concerend, in raid 5 one disk act as parity. So our data is safe with disk failure.

With raid1 (conisdering 4 disks) you can sustain 2 disk failures; But the effetctive space you get with raid1 is 50%.

[Maaz]

Thanks Santhosh Kumar Theyyan for help

If i add 2(total 5 hdd) more hard drives, destroy the default raid-5, and then installed the Linux OS on raid-1 volume that consist upon sda, sdb, and sdc(here sdc is spare).
Likewise create another raid-1 volume that consist upon sdd, sde, and sdf(here sdf is spare).
And configure the swap on a traditional volume e.g on sdg.

what you guys suggest, as I need both the fault-tolerance/redundancy as well as Read/Write speed too. will the above plan gives me the best of both(redundancy/fault-tolerance and Speed).

I am very soon going to Install a server, and by asking I am preparing the best procedure for my enterprise.

[Steven E. Protter]

Shalom,

Raid 1.

More reliable.

Faster, especially in a heavy write environment, which an email server may be. You point out the flaws in RAID 5 very nicely.

More than likely if you lose two disks your raid 5 system is dead. Depends how many disks are in the RAID group.

SEP

[Venilton Junior]

I recommend to use the all 04 disks together, using them in RAID 1+0.

If you use this type of array, you'll have 04 disks working in WR+RW.

Using all of them together, just split your /, /var and other mount points, among partitions.

Yes, u'll have fault tolerance with this arrange and even if you have a fault, won't impact in your environment.

Best luck

Regards

[Maaz]

Dear Venilton de Carvalho Jr
>I recommend to use the all 04 disks together, using them in RAID 1+0.

I thinks RAID 1+0 means a non-physical raid 0(stripe volume)that consist upon atleast two RAID 1 volumes.. isn't ?.

you mean I should create two raid-1 volumes
1st raid-1 volume: sda, sdb
2nd raid-1 volume: sdc, sdd

then create a raid-0 volume that consist the two raid-1 volumes .. isn't ?

Did the ML 350 G5 RAID Controller Software, provides the feature of creating RAID 1+0, or I have to create two raid-1 volumes, using ML 350 RAID Controller program, and then during Installation of the OS, create a Software RAID-0 that uses the two hware raid-1 volumes ?


>just split your /, /var and other mount points, among partitions.
Did you mean that on a RAID 1+0, I create two partition one for Linux OS(/) and the other one for user's mailboxes(/var/spool/mail) ?

Regards
Maaz

[Venilton Junior]

Maaz,

You said that you have SATA drives. I don't remember if ML350's sata controller can do 1+0. I'm sure that for SCSI and SAS the controllers can do it.

But explaining about RAID 1+0. I'll take the example of SAS disks. If you have four disks of 146 GB, you have a logical volume of 292 GB with fault-tolerance. Resuming, u'll have mirroring+stripping.

>just split your /, /var and other mount points, among partitions.
Did you mean that on a RAID 1+0, I create two partition one for Linux OS(/) and the other one for user's mailboxes(/var/spool/mail) ?
Yes, you can put all together, to use all performance of your disks.

Another way to do it, is like you said, two volumes of RAID 1 and do stripping in your OS with LVM. But I would recommend to do RAID 1+0 if posible.

Best luck

Regards

[Maaz]

Thanks Venilton de Carvalho Jr.

No problem I can order SAS drives too.

ok suppose I have the 4 SAS drives, then using ML 350 RAID utility, first I'll create two RAID-1 volumes as:
1st raid-1 volume: sda, sdb
2nd raid-1 volume: sdc, sdd

then using the ML 350 RAID utility create a raid-0 volume that consist the two(1st + 2nd) raid-1 volumes .. isn't ?

Regards

[Venilton Junior · Accepted solution]

No.

In the ORCA, you can select all of your four drives and do a RAID 1+0.

As an example: If you have 4 x 146 GB SAS Disks, you'll have an array of four disks in RAID 1+0 and a logical volume with 292 GB of total.

In your gonna install Linux, you'll see this 292 GB as a single disk.

In this space, you can have your swap partition, / and your mailbox location.

In this configuration you can have the troughput of four disks working together, also with performance of RAID1 and RAID0.


Here you can find more information about RAID ADG, 1+0 and 5.

Also, check the attach file for further information.

Regards