Recommended file system for database

[KKJensen]

Hi there,

Still climbing that linux learning curve but things are coming along very well...

I have a question regarding file systems. FC5 (default install) uses ext3 filesystem. I'd like to put the scalix stuff onto the best file system possible. I have two extra identical 7200rpm drives (20GB each). I have a few questions.

My mobo has an onboard raid controller that "seems" (haven't tested it extensively yet) to be supported by linux as the two drives do show up in /dev when in IDE mode and only one drive shows when I set the bios to RAID mode. Is hardware RAID preferable over software RAID??? I used to do some windows 2000 software raid for striping these drives together...it wasn't as fast as hardware but saved me the headache of dealing with drivers etc etc...I'm curious as to the benefits of letting linux run the raid array vs the bios. I would like to mirror the drives for redundency. 20GB will be plenty for the <20 people we have working in the office.

File systems: I notice that my /var/opt/scalix/ll/s/data directory is full of 4.0k files...I read that the ReiserFS is recommended for drives with lots of files under 4.0k since it's performance is measured to be very significantly faster than the others. Is this true and would it be best to put the scalix installation onto a partition with the ReiserFS? This is the tutorial I read it on: http://www.linux-noob.com/forums/index.php?showtopic=1902 ...FYI

If I have an existing scalix installation on my first (slower) drive, hda...how can I migrate it to the newly mirrored (hardware or linux) drive and mount it back to the file system as /var/opt/scalix? I've done some simple copying etc and partitioning but I have test users helping me watch for bugs. The problem is I don't have the confidence yet to fire off any large, grandiose commands that will migrate everything to the new drive and get things operational again quickly...I would only have a couple hours after everyone else leaves to pull it off and have it ready for the next workday.

Thanks in advance for any help you have to offer.

[straylight23]

Hi

[list]My mobo has an onboard raid controller that "seems" (haven't tested it extensively yet) to be supported by linux as the two drives do show up in /dev when in IDE mode and only one drive shows when I set the bios to RAID mode.

This looks promising, although this will "only" be hostraid. I don not like them really, because the boxes i know running host raids, do tend to fail more often then the ones with "real" raidcontrollers like 3ware, icp etc.

Is hardware RAID preferable over software RAID???

I would always prefer hardware raidcontrollers, because of reliability,stability and performance. But YMMV.

File systems: I notice that my /var/opt/scalix/ll/s/data directory is full of 4.0k files...I read that the ReiserFS is recommended for drives with lots of files under 4.0k since it's performance is measured to be very significantly faster than the others.

The more you search, the more benchmarks you'll find showing all different results. Me personally would stick to ext3, because it ist available in all stock kernels in all distributions.

If I have an existing scalix installation on my first (slower) drive, hda...how can I migrate it to the newly mirrored (hardware or linux) drive and mount it back to the file system as /var/opt/scalix?

This could easily be done with tar or rsync. The following is a quick and dirty explanation for thet tar thing and assumes you have the old diks mounted on /var/opt and the new disk mounted on /var/opt2

#service scalix stop - to assure sxalixstorage is consitent
#cd /var/opt
#tar cf - scalix | (cd /var/opt2 ; tar xpvf -)
#umount /var/opt
#mount /dev/newdisk /var/opt
#service scalix start

That's basicly it ;)
Regards,
Tom

[dresdn]

No matter who you talk to, any competent admin will prefer hardware RAID over software. If costs/space prohibit, then software RAID is better than no RAID.

File systems: I notice that my /var/opt/scalix/ll/s/data directory is full of 4.0k files...I read that the ReiserFS is recommended for drives with lots of files under 4.0k since it's performance is measured to be very significantly faster than the others.

The more you search, the more benchmarks you'll find showing all different results. Me personally would stick to ext3, because it ist available in all stock kernels in all distributions.

You're correct in the fact that ReiserFS would be the preferred file system, but I would strongly recommend against it since ReiserFS is going the way of the Dodo, ie. Novell and Suse have both moved away as the default fs type. The future of Reiser is in question with the arrest of the creator. Basically, I wouldn't bet on it, esp with the way ext4 is shaping up to be.

-Mike

[KKJensen]

arrest of the creator

LOL!

[KKJensen]

I've been reading up on Reiser ever since I first posted...looks like it's not the greatest choice if I'm on FC.

I've been trying to find a link to a good SATA HW RAID card on the web that is 100% supported by FC5 but haven't had much luck...any recommendations for vendors or brand names? With SATA2 drives dropping in price, the notion of spending a few hundred bucks for a redundant raid array is quite appealing...a lot nicer than fooling around with software...

#service scalix stop - to assure sxalixstorage is consitent
#cd /var/opt
#tar cf - scalix | (cd /var/opt2 ; tar xpvf -)
#umount /var/opt
#mount /dev/newdisk /var/opt
#service scalix start

I made a type....meant to say /var/opt/scalix/ not /var/opt/scalix (It's a whole directory, not just a file). Could you give it to me but moving the whole directory and not just a file?

I don't really follow what the tar line is doing so I'll wait and try and decipher it once you've responded. I'm going to go "man tar" for a little while while I wait.

[straylight23]

I
I've been trying to find a link to a good SATA HW RAID card on the web that is 100% supported by FC5 but haven't had much luck...any recommendations for vendors or brand names?

I had a lot of luck with those 3ware controllers. And - if you consider buying new drives - do buy four of them and do a raid10

#service scalix stop - to assure sxalixstorage is consitent
#cd /var/opt
#tar cf - scalix | (cd /var/opt2 ; tar xpvf -)
#umount /var/opt
#mount /dev/newdisk /var/opt
#service scalix start

I made a type....meant to say /var/opt/scalix/ not /var/opt/scalix (It's a whole directory, not just a file). Could you give it to me but moving the whole directory and not just a file?

The tar command above will "compress" the whole directory "scalix" into stdout and extract it in /var/opt2 on the fly. Hint: try to google for "tar pipe".

HTH,
Tom

[dkelly]

We don't particularly have a preference for file system but we definitely do for RAID configuration.

We're trying to find a way to get this better communicated in places where people will actually read this stuff so, over the next few weeks, we're blanketing this advice in our documentation...

Our recommendation for RAID configuration is RAID 1+0 with SCSI disks and no write cache.

Scalix doesn't use a database and RAID5 is optimised more for that environment. RAID 1+0 is optimised for smaller reads/writes and because Scalix is an IO-bound application, there are lots of writes to disk for small files, as has been commented previously.

It's been our experience with a number of installations that any combination of SATA/RAID 5/Write Cache has impacted performance. Write Cache has been seen to cause corruptions in some cases where it appears that the cache is not flushed correctly. When we write to disk, we issue a sync so that we flush any disk buffers. It's been the case where the disk subsystem has reported that the buffers are flushed but the underlying hardware has, in reality, just cached it.

Cheers

Dave

[KKJensen]

I'll look into those controllers.


If the tar line packs up the scalix directory from the /var/opt/ directory to the /var/opt2 directory, when does the info actually make it onto the new RAID partition?

Why do we umount /var/opt/ if it is: 1.empty 2. /var/opt/scalix that is being moved? Won't this cause problems with the other directoreis in /var/opt? Perhaps moving all of /var/opt is better instead of just /var/opt/scalix?

The mount command I understand...mounts the new drive to the /var/opt directory (this is part of why I got confused about the whole umount thing...I didnt' know what umount would do with an empty directory.

Thanks for the help. I'm sure your code will work fine...I just don't like running any procedure that I don't at least understand a little bit.

[dresdn]

I've been trying to find a link to a good SATA HW RAID card on the web that is 100% supported by FC5 but haven't had much luck...any recommendations for vendors or brand names? With SATA2 drives dropping in price, the notion of spending a few hundred bucks for a redundant raid array is quite appealing...a lot nicer than fooling around with software...

I agree with Dave, 3ware is the way to go for SATA HW RAID. I've never had a problem with Linux not supporting it nor with the controller itself.

-Mike