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HSM or SAN?

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by ttate 1 view

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Is Hierarchical Storage Management (HSM) better or Storage Area Networks (SAN) for maintaining storage resources?

SANs have become the new thing and are very expensive and proprietary right now. Is HSM alive and well? How does it integrate into a mixed Novell & NT environment? What solutions exist for HSM?

Thanks for the help & advice!

7 replies

by steffen.hornung

So we have to define HSM and SAN:
HSM is meant to be a scheme of having unaccessed data stored nearline or offline in order to prevent from upsizing your disk space all the time. HSM stores data hierarchical (as the name says) - this means:
you have data that was not touched for lets say half a year; so HSM moves data from your expensive RAID5-system to cheaper CD-Library (burns data to CD). Your CD-Library though will fill up and before you buy another HSM stores this data maybe on DLT-tape or other MO/DVD and you put this tapes/disks to your safe and your data is now offline. If a user needs that data, HSM requests the appropriate medium and stores it back to your harddisk. This is HSM in short.

SAN on the other hand is a technologythat enables you to attach a harddisk or diskarray direct in the network - without a server that manages this data. SAN-devices typically have a webbased console. You give them a IP-Adress, set the security parameters and take the disk online. This is SAN.

So we are talking about absolut different technologies!
SAN-devices have to be backed up too. But no server is attached! So new Backupsoftware has to support that devices. CA Arcserve 2000 e.g. does!
HSM is alive and well (although I cant remember to have seen an installation anywhere). HSM has to be supported by your Network OS (Novell does, NT I am not sure) and your backupsoftware (Arcserve does - others I don't use, but the homepage of your backup-software-vendor should tell).

by ttate

I don't think you fully understand SAN vs NAS. I think you are describing Network Attached Storage, not Storage Area Network. These are two totally different concepts. You are right on target w/ HSM though. I am looking for a valid HSM installation and the gotchas that go with it. Which is cheaper over the long-run, HSM or SAN? Which is more reliable over the long-run, HSM or SAN?

Thanks for your time.

by printermanager

>>Which is cheaper over the long-run, HSM or SAN?
with very high volume: HSM

>>Which is more reliable over the long-run, HSM or SAN?
SAN.

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HSM: My Bad experiencie.
I used a DLT7000 library as second level HSM. Well a "bad-callibrated" DLT7000. All DLT cartridges was write by a "bad-callibrated" DLT7000.
When my DLT7000 was broken by a accident and was replaced by a new DLT7000, none of all off my HSM-DLT cartidges could be readed.
Anything can go wrong??

Do you like acheaper or a reliable solution?

by ttate

This is very interesting information and a very good question that you raise. Reliability should be the first and foremost thought when purchasing any equipment that needs long service. I'm sorry about your experience, but it helps to have a backup plan in case the first plan doesn't work to begin with.

Thanks for your time.

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