what are experiences of using ssd instead of u320 scsi hard drive?

our server has 70Gb scsi drive, and I would like to recommend my boss switch to sata/ssd (with ARS2320H)

It will really depend on which SSD you go with, and your workload. The lower end consumer SSD will probably not do much to improve performance in the long run. Also I don't know how putting a SCSI to SATA bridge in the mix would impact things.

Generally speaking for a high quality SSD and a highly random IO workload the SSD will beat SCSI.

hm, I was considering Intels x25-m. unfortunately its not SLC, but they say still very fast. and not too expensive.

we are using database on that server, and it tends to get 'sluggish' after a while.
I know ssd is not a real solution (to a mostly software problem), but hope it might help.
at least we wouldn't have to think about defragmenting.

Databases are generally one of the better uses for SSD, so that seems like it should be a good match. What is the current disk setup?

Also the latest generation Intel MLC drives are one of the better choices for an affordable SSD solution. I think the biggest question which nobody would be able to answer is how the SCSI to SATA adapter will impact performance, you will need to do some testing on your setup and make sure it doesn't kill performance.

Have you already done the typical DB optimization stuff such as putting logs and data on different physical devices? Are you sure it is really IO bound and not memory or CPU?

well the hard disk is mostly empty. so we might be even able to replace it with 40Gb with no space problems at all. but I've heard that ssd gradually loses writable blocks as it 'ages', so does that mean larger drive would last longer?

our database is very mostly used for reading, not writing. but there is swap partition, ofc.
about logs, we already disabled some as they filled up the disk. but there are some other that probably should be disabled too.
every now and then I backup one log with ftp and delete it from server (grows quickly). but its not really used. ideally, it would be redirected to ftp.

there is just one physical drive in server, and I wish to keep it that way (heating, electricity...)

I'm sure you all understand what you are saying, but it bothers me that the language used seems to be confusing transport with media. SCSI, SATA and SAS are storage interfaces. Disk drives and SSD can use various storage interfaces. So, asking if SSD or SCSI is better is a non sequitur.

SCSI, in it's traditional form, is becoming less common. The choices are more likely to be SATA or SAS. The storage systems I use are enterprise class SAS and can take either SAS or SATA devices, and either disk or SSD. The SAS is multi-homed and driven from a PCI card added to the server.

So, start by asking what interfaces your server supports or what can reasonably be added if you choose to. Then start looking at cost and performance of the alternatives. Using large SATA drives for, say, image stores where the data doesn't change often, but you need lots of storage, makes sense. Using less large, faster SAS drives for system critical stuff that changes frequently and is accessed frequently makes sense. Using SSD for ZFS write intent buffers, or for some databases, also makes sense. In a server setting, I would use SAS. Most desktops use SATA disk drives, and some of the smaller, faster personal devices, e.g. the MacBook Air, use SATA SSDs.

hm, server uses Ultra160 SCSI host adapter, and ARS2320H is Ultra320. so I presume it should be fast enough.
thanks for the advices, but I dislike SAS for same reasons as: SCSI, firewire, displayport, thunderbolt..