what's Best filesystem for SAN

[ganaiwali]

what should be the best pick on the file system type for a host connected to SAN of 1TB via Fibre channels .e.g CentOS 64 , 64G RAM HP / PROLIANT / DL380-G7 , the app will write files of size , say 200 to 250 MB each..

I understand there is a choice of GFS / GFS2 ( should I consider GFS2 ? )

also there is XFS and vxfs which again are GFS but i want to understand which would be the BEST choice and why ...


thx,
Tariq

[Zinky]

It depends what USE you want to make out of the "filesystem".

For plain jane untructured file storage (aka a File Server) the normal ext3/ext4 should suffice.

If you want a Cluster Filesystem with data available R/W on a "Cluster" of nodes then you undoubtedly have a myriad of choices with varying "it depends". Your choices are:

GFS2
Require's RHCS (RedHat Cluster Suite)

LUSTRE
Google.

GPFS
IBM's tried and tested Cluster Filesystem

OCFS2
Oracle's simpistic Filesystem.
Google it too.

VxFS
Needs Veritas Cluster Server of course.

[Don Mallory]

If you aren't planning on clustering the host, and you are using a SAN with such a small size (1TB only?) with files in the 200-250MB size range, then honestly, I'd stick to plain old ext3.

XFS is great if you are looking for a large filesystem (far > than 16TB), same goes for most other clustered FS.

If you google up filesystem performance tests, there have been a large number, some are more reliable than others, but ext3 comes up pretty close or on top a lot of the time.

The only thing to remeber is to turn off the automated filesystem checks (tune2fs -c 0 on your FS.)

You can even use LVM, it really doesn't matter. Adding volumes, just present more 1TB LUNS and away you go. If you present a bunch at the beginning, you can stripe them.

Best regards,
Don

[Zinky]

"You can even use LVM, it really doesn't matter. Adding volumes, just present more 1TB LUNS and away you go. If you present a bunch at the beginning, you can stripe them."

LVM is NOT a filesystem.It is a volume manager.

If your are ext filesystem bound and on newer CentOS/RHEL 6.X -- ext4 is your best bet for simple non clustered filesystem.

For a CLustered Filesystem -- again YMMV and it will depend on your (1) use - gazillion small files or not (2) expertise on the underlying cluster scheme of volume manager and (3) budget.

If you have deep /good budget and aer gunning for an industrial strength solution -- my recommendation is either IBM GPFS or Veritas Cluster (VxFS)

Cheers.

[ganaiwali]

thanks for your reply folks , just to clear that these systems are not going to be in any cluster , however we are looking at scaling our storage to more TB's in an year or so .So its my understanding that we might take advantage of xfs which has worked just fine on some of the existing systems (only that we need to get our kernels to support xfs ) . I am not so sure about the ext3 on SAN though .

[ganaiwali]

Alzhy,


appreciate your support , ext4 even though is officially released and claim is stable, but there still seems to be a lot of development going on and guess is not really suitable for prod environment especially with 100's of multiple huge files plus I am not sure about its compatibility with centos 5.2 and above .

[Zinky]

I hear ya... ext4 is considered a Technology Preview on RHEL 5.X (CentOS 5.x) but NOT on RHEL 6.X -- so base your decisions on that I guess.

Lastly --- filesystems ext3,4,vxfs,ufs, etc MATTERS not whether the disk is local SCSI, local RAIDED scsi, SATA, SSD, SCSI or SAS (heck even IDE) or even SAN.

So your concerns about ext3 on SAN is largely unfounded. What you NEED to totally be intimate about is how Linux is properly configured to acess/utilize/multipath and volume manage your SAN Storage/disks.

And lastly - your Readings and adventures should include -- LVM and device mapper multipath (aka multipathd) as well as your SAN vendors "recommended multipathing proprietary solution" if they do not prefer Linux's native multipathing.

Cheers and Ciao!

[ganaiwali]

we are going with ext3 .

[Don Mallory]

Tariq,

You may also want to read up on udev. DMMP and many of the other proprietary multipathing layers use udev style device files to manange and build out dynamic paths. It's not as important if you choose a commercial product, but understanding what it's doing will help you if the native DMMP components don't seem to be working as you would suspect.

Also, be aware that some vendors' proprietary solutions support multiple vendor's SANS. VxVM w/ DMP (supports almost anything) and EMC PowerPath (supports Hitachi, EVA, IBM, EMC CX/Sym/Invista arrays) are good examples.

Alzy, you are correct, LVM is a volume management archticture. I can see how it may have been interpreted that I was suggesting it was a filesystem. Thanks for clarifying for Tariq.

Best regards,
Don