Topic: SME on Compaq Proliant ML570 ?

[Agent86]

Has anyone installed SME on a compaq proliant ML570 with lets say 4) P111 xeon 1GHZ processors and 12 scissi 36gb drives ? or similar configuration.

I recall reading something about the raid config, and am trying to decide on letting the server handle the raid or let sme handle the softraid. I'm not really sure how SME is designed to work with this type of hardware configuration. I'm only familiar with the 2)IDE drives and softraid configuration.

Basically I'm attempting to have the server acting as 2 drive capacities, one array of 6 drives as the first capacity and the second array of 6 drives acting as the backup or second capacity.

And I'm guessing if I can configure it this way, that in the event of a single drive failure, then the system would continue to work and I could just pull out the bad drive and swap it with a new drive, ? Does SME work with the hotswap capability on this ML570 also ??

Also would SME utilize the 4) processors ?

What would you recommend ?

[pherder]

I have always heard (read) that hardware raid is much better than software raid (speed and transparent to the OS).

I have two Compaq servers, one a DL380 and a 1850r (both dual processors, the DL380 has dual 3.2GHz and the 1850r has 600MHz processors) with 6 drives in each, setup with 5 drives Raid 5 with the last as a hot spare. 

SME only sees one drive in both and if I have a failure, the hot spare is suppose to be used by the RAID controller to replace the bad drive.  If I have two bad, I still am suppose to have full access to the data and can hot swap the drives.  The OS doesn't see hardware RAID, it just sees the logical drive(s) that are setup outside of the OS so it doesn't know about or care about hot swapping drives unless you have a failure that destroys the RAID data (i.e. 2 drives fail in an array of 3 drives ... the smallest RAID 5 combo.

Haven't had a problem, yet. {fingers crossed }

Can't answer your question about 4 processors and the OS, don't have it so I haven't looked.

Do know that if you have two logical drives, the SME server will try to configure them as a RAID1 (mirror) drive if they are the same size.  Or complain about them if you don't allow the OS to configure them as RAID.

I have a USB drive attached to the DL380 to do backup to and I get an error emailed to me (after a boot) stating that I have a redundant drive error (it sees that I have two logical drives but they are not being used by the OS as a RAID drive.  I have been ignoring the error since I know why it is happening.

I have seen posts that talk about using two separate logical drives on a SME server but again, I am not using one (except for backup) so I haven't deal with working with them.

HTHs.

[Agent86]

Thanks,

I'm wondering if I should use the 6 drives for one capacity and 6 for the other, and then I'm not sure what thats called, Raid 0+1 or something ?  or is Raid 5 better?

I'm not oppose to raid hardware method, but it's more drives then I"m use to and I've been using IDE drives, so this is a little alien to me.

Any suggestions on how I should configure this system would be great ? I'm guessing I can access the scissi controller and create the array's that I want ?
Do I need to turn off the soft raid in SME ? if I decide to use hardware raid ?

Thanks again.

[pherder]

Depends on how much storage space you want.

I.e. I have 6, 36 GB hot swap drives configured as 5 drives as RAID5 (total storage space of 98 GB) with one hot spare.

If I had 12 drives, all 36 GB, I could have 2 hot spares, 5 in RAID5 (one logical drive) and the other 5 in RAID5 (second logical drive).  All this before the OS even sees the drives (2 logical).  At this point I would have two logical drives of 98GB each.

Now if I let the SME server do it's thing, it would see the two logical drives as exactly the same size and make them 1 drive, mirrored (software RAID 1 or maybe 0+1... see http://en.wikipedia.org/wiki/RAID for more info).  The OS would show only 98 GB of total drive space due to mirroring.

My feeling is that is sort of a waste of drive space ... you already would have RAID5 in hardware (redundancy) and now you would have software RAID mirroring (Redundancy on Redundancy).  There may be a good reason to do it...   

All this is guessing that you have a hardware RAID controller available.  If not, then the OS will default to a RAID configuration depending on the number of drives it sees when you are installing the OS.

BTW, I AM a SME noob having only had my systems up for ~ 4 months so do your reading on the server docs online.  It got me going without having to ask any questions (I do have 27 years with microcomputers so that helped!

This OS has been the best Linux I have used.  It hasn't treated me like the windoz weinie I am!   

[Agent86]

Oh, I see, so the hot swap hot spare is should basically take over in case of a failure, and this way no need to mirror the complete volume of the 5 drives ? I was not sure I understood that,

So if you had 12 drives you could have a dual 5 drive setup with 2 hot spares is that what you mean ?

But why is the capacity only 98 GB ? shouldn't the 5 drives give you like 180GB or about ??

Thanks for the help this has been helpful

P.S now if anyone could advise weather or not I would even need or want 4) processors ? or if this would increase performance ? or if SME would even utilize the 4)processors ? That would be great, I'm not sure I'll even use this server, but I'm researching to determine this
Thanks

[m]

So if you had 12 drives you ....

...should build a RAID-6 array of 11 disks + 1 spare. Then you get a net capacity of (11-2)*36G=324G. If you don't need that much capacity use more spares (and put them on stock to save power).

P.S now if anyone could advise weather or not I would even need or want 4) processors ?

Nobody but you can give the answer. If your server will act a simple file server for a few users, 4 cores are overkill. On the other hand, if plan to host many virtual machines, a 4 core server could be undersized.

if SME would even utilize the 4)processors

Far away from the limits. SME7 is based on CentOS4. See www.centos.org/product.html

[Agent86]

...should build a RAID-6 array of 11 disks + 1 spare. Then you get a net capacity of (11-2)*36G=324G. If you don't need that much capacity use more spares (and put them on stock to save power).
Nobody but you can give the answer. If your server will act a simple file server for a few users, 4 cores are overkill. On the other hand, if plan to host many virtual machines, a 4 core server could be undersized.
Far away from the limits. SME7 is based on CentOS4. See www.centos.org/product.html

Great thanks, so it appears to support 32 CPU's x86 type.

My machine is mostly file server, and webserver, and webmail. so I should be good, even with a P111 4x 700MHZ processors.

I really need to research this a bit more about raid, I've read thru the wiki stuff, but I'm not sure I understand the concept of the spare, not being the same size as the array, ? Can you give a brief overview of this so I can understand how it work, and understand the wiki's a bit better.

Thanks again for the help this is great info.

[Agent86]

One more thing, how do people feel about Raid 1 vs Raid 5, Since the Raid 5 appears to be mostly the capacity with a spare or 2, is this the most typical for servers ? or is Raid 1 more typical or perhaps Raid 10 ?

I realize I have to decide on this but there seems to be too many choices I'm having some trouble deciding.

I'm using simple software raid built into SME on IDE drives, now, so I'm happy with that, and I guess Raid 1 could be well enough for me, but I understand the performance is faster, but then again why should I use all my drives if I can increase capacity and use a spare or 2, and get the same results. I guess my biggest topic of concern is reliability.

Will Raid 5 or Raid 6 be as reliable and safe as Raid 1 ?

Please advise Thanks