Tuesday, January 20, 2009

Things to know before you build an OpenFiler SAN

These are some important tips that you may want to know before you go and choose the hardware that will run the OpenFiler software, if you do not want OpenFiler to be just a play toy:

  1. Do not run OpenFiler on a desktop PC.
  2. If you must use a desktop PC, use only Intel hardware (CPU, mainboard and network cards). Leave away any system that has nVidia, ATI, VIA or AMD hardware. The network cards can also be from Broadcom. Do not use network cards from Realtek, Marvell or others, put them on your usual desktops, not in your SAN.
  3. Choose only "jumbo frames" enabled network cards from Intel/Broadcom. Search also for "teaming" or LACP or 802.3ad capable network cards. Do not forget that the switch also needs to know about these features.
  4. Check all the chosen hardware against the RedHat HCL - https://hardware.redhat.com/. Do not use the hardware if is not on the RHEL HCL.
  5. Do not use the latest and greatest of hardware, go for at least a year old hardware before the current kernel.
  6. If you decide to buy some server (new or used), choose a server from a big server vendor: Dell, IBM, HP, Fujitsu-Siemens, Supermicro and others.
  7. Do not use the RAID features implemented in chipset or add-on cards, expose every disk to the OpenFiler and use the software RAID implemented in OpenFiler. Buy simple add-on card for adding drives to the OpenFiler box, without RAID. If you do not find cards without RAID, disable the onboard RAID features.
  8. For SCSI, use Adaptec, LSI Logic or AMI controllers. For SATA, use Silicon Image, Marvell or Intel AHCI controllers. Avoid JMicron and the likes.
  9. Do not use USB or FireWire attached disk drives to use them as the main storage! Use them only for backup. Using OpenFiler on USB and FireWire disks will eventually result in tears.
  10. Try to use SCSI/SAS disks. If you use SATA disks, use Seagate ES, Western Digital Enterprise/Raptor or Hitachi drives. If you must go with other brands/models, search for NCQ enabled drives.
  11. Size your power supply carefully, SATA drives are particularly sensitive to voltage drops on the 12v rail. Choose a high quality and powerful PSU.
  12. If you value your data, you must use a UPS on your OpenFiler system.
  13. For the file system, use XFS. XFS is extremely resilient to faults, dirty shutdowns and other maladies that can cause data corruption.
  14. Install Openfiler on a RAID1 set of drives, if one drive will fail your SAN will continue to work.

Keep in mind that OpenFiler is designed to store information. Sometimes very important information. Reliability is therefore the most important aspect of using OpenFiler, unless you don't mind losing data.

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