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iSCSI

iSCSI. iSCSI Terms. An iSCSI initiator is something that requests disk blocks, aka a client An iSCSI target is something that provides disk blocks, aka a server. An iSCSI portal is the combination of the IP and Port of a target. Terms. Portal: 172.20.81.5/3260. Initiator. Target.

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iSCSI

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  1. iSCSI

  2. iSCSI Terms • An iSCSI initiator is something that requests disk blocks, aka a client • An iSCSI target is something that provides disk blocks, aka a server. • An iSCSI portal is the combination of the IP and Port of a target

  3. Terms Portal: 172.20.81.5/3260 Initiator Target Windows/Linux/OSX box, Mounting the target as A block device Linux box, providing a disk as an iSCSI target

  4. Terms • In this case, the target is a linux box running the iSCSI daemon. The IP and the port the daemon are listening on are the portal. Any device that can act as an iSCSI initiator can connect to the portal and treat the device as a block device • The space served by the target is a raw disk device

  5. iSCSI Setup • On the server side, setup is still somewhat nasty. • iSCSItarget.sourceforge.net has a linux implementation of iSCSI • You need to recompile the kernel; kernel 2.6 or more recent is required • Yum update kernel kernel-devel to get the necessary files • Export KERNELSRC=/usr/src/kernes/2.6.14… • Make, make install • Init scripts installed in /etc/rc.d, /etc/init.d

  6. iSCSI Target • Target address format: • Iqn.2004-04.edu.nps:storage.something.here • “iqn” is the type (iSCSI Qualified Name) • 2004-04 is the date of the first full month the naming authority was registered • Edu.nps is the reversed domain name, the naming authority • Storage.something.here is a name assigned by you • Basically, you only have to worry about the last field

  7. Etc config • In /etc. ietd.conf controls name • Target iqn.2001-04.iscsi.ern.ps.edu:storage.iscsi.file • Lun 0 Path=/dev/sdb • /etc/iscsi has some other config parameters

  8. Client Side (Initiator) • Now that the target (provider of disk space) is set up we can configure the client. • On Windows, get the MS iscsi initiator (google) and run the installer • Start iSCSI initiator and specify the IP and port to connect to

  9. Discovery/Portals

  10. Targets Note that the name matches the name we provided in the ietd.conf file--we connected successfully

  11. Disk • At this point we have block device access to the device. On another system I created a FAT filesystem, so we can also show this as a FAT drive. • NOTE: If two machines have block access, they WILL eventually put the FAT filesystem into an inconsistent state. Ditto for ext, zfs, ntfs, and other single-host filesystems

  12. iSCSI on OSX • Supposedly iSCSI was going to be part of Leopard--it didn’t make it. Probably be added at some later date • There are free iSCSI initiators available, http://www.studionetworksolutions.com • Run installer; adds a .kext kernel extension, which requires a reboot

  13. globalSAN Note IP and 3260 port

  14. GlobalSan Connection established; note match of iscsi ID with that of the target config file

  15. Filesystem Creation • Once you have access to the iSCSI drive as a block device, you can create a filesystem on the device.

  16. Filesystems • Again, conventional filesystems are designed to have only one OS access them as a block device. • We can have multiple hosts contact the iSCSI block device. A conventional filesystem will eventually become inconsistent if you do writes from multiple hosts

  17. What did we get? • We accessed a block device on a linux server from OSX and Windows across an IP network using commodity ethernet (or wireless) protocols. • This isn’t quite a SAN, since we don’t have volume management, but it provides the substrata needed for that

  18. Volume Management • This is somewhat tricky and still a developing field. There are a number of commercial implementations and a few open source implementations • This is the layer that handles concurrent access to block devices

  19. Architecture • What would a cluster architecture look like with a SAN?

  20. iSCSI devices • No endorsement implied by any mention of a vendor, prices variable…. • Promise vtrack: ~$5K for enclosure, plus disk • 16 SATA bays, 3U, RAID, TCP Offload Engine

  21. iSCSI Devices • HP Storage Works AIO 1200, 600, 400 • SATA or SAS drives possible • http://h18006.www1.hp.com/storage/aiostorage.html?jumpid=reg_R1002_USEN • ~ $8K for 3 TB

  22. iSCSI • Sun is generally dismissive of iSCSI for their enterprise storage products • EMC has an installed base in FC, though they do offer iSCSI in parallel on some boxes • EMC is partnered with Dell: AX150 (12 SATA drives, 9 TB, RAID) $11K for 1.5TB (Massive discounts probably apply) • CX3 series: up to 144TB, enterprise stuff

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